High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film ha...High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.展开更多
In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize...In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize the sample quality and the antiferromagnetic transition temperature T_(N).By substituting In with Ga,T_(N) is slightly decreased,but the antiferromagnetic transition peaks in magnetic susceptibility and specific heat measurements are obviously broadened by external field along c-axis.By comparing with Zn-doped Ce RhIn_(5),it can be concluded that T_(N) is dominated by electron density,and the stiffness of antiferromagnetic transition is obviously reduced by Ga substitution.The substitution effects of Ga are possibly caused by forming heterogeneous local structures,which avoids quantum critical point,superconductivity,and non-Fermi liquid states.Investigations on Gadoped Ce RhIn_(5) help to comprehend the chemical substitution effects in Ce RhIn_(5),and the interaction between heterogeneous structure and long-range antiferromagnetic states.展开更多
We investigate the origin of the 1/3 magnetization plateau in the S=1/2 kagome antiferromagnetic Heisenberg model using the variational Monte Carlo and exact diagonalization methods,to account for the recent experimen...We investigate the origin of the 1/3 magnetization plateau in the S=1/2 kagome antiferromagnetic Heisenberg model using the variational Monte Carlo and exact diagonalization methods,to account for the recent experimental observations in YCu_(3)(OH)_(6+x)Br_(3-x)and YCu_(3)(OD)_(6+x)Br_(3-x).We identify three degenerate valencebond-solid(VBS)states forming a√3×√3 unit cell.These states exhibit David-star patterns in the spin moment distribution with only two fractional values-1/3 and 2/3,and are related through translational transformations.While the spin correlations in these VBS states are found to be short-range,resembling a quantum spin liquid,we show that they have a vanishing topological entanglement entropy and thus are topologically trivial many-body states.Our theoretical results provide strong evidence that the 1/3 magnetization plateau observed in recent experiments arises from these√3×√3 VBS states with fractional spin moments.展开更多
Multifunctional semiconductors play an important role in developing advanced photoelectric technologies.In this work,based on an octahedral replacement strategy in chalcogenides,a new selenide semiconductor NaMn_(3)Ga...Multifunctional semiconductors play an important role in developing advanced photoelectric technologies.In this work,based on an octahedral replacement strategy in chalcogenides,a new selenide semiconductor NaMn_(3)Ga_(3)Se_(8)was rationally designed,and synthesized by the flux method.The compound crystallizes in the noncentrosymmetric(NCS)P_(6)space group,and is composed of unique prismatic[NaSe_(6)],octahedral[MnSe_(6)]and tetrahedral[GaSe_(4)]motifs,inheriting the stable three-dimensional framework built by the octahedral and tetrahedral units in the A^(Ⅰ)Mg_(3)^(Ⅱ)C_(3)^(Ⅲ)Q_(8)^(Ⅵ)family.NaMn_(3)Ga_(3)Se_(8)shows the largest known secondary nonlinear optical(NLO)response of~2.1×AgGaS_(2)(AGS)in the A^(Ⅰ)Mg_(3)^(Ⅱ)C_(3)^(Ⅲ)Q_(8)^(Ⅵ)family,and a high laser-induced damage threshold of~3.0×AGS.Meanwhile,the introduction of Mn2t with unpaired 3d electrons induces a strong red emission band(685–805 nm)under the excitation source of 496 nm,as well as a paramagnetic to antiferromagnetic(AFM)transition at 7.3 K.The results confirm that NaMn_(3)Ga_(3)Se_(8)possesses multifunctional features including significant NLO response,fluorescence emission and AFM properties,and illustrate that replacing octahedral units with approaching size and geometry(like[MgSe_(6)]and[MnSe_(6)])could be a feasible way to develop multifunctional chalcogenides.展开更多
The ground-state magnetic ordering of uranium mononitride(UN)remains a contentious topic due to the unexpected lack of crystallographic distortion in the traditionally accepted 1k antiferromagnetic(AFM)state.This disc...The ground-state magnetic ordering of uranium mononitride(UN)remains a contentious topic due to the unexpected lack of crystallographic distortion in the traditionally accepted 1k antiferromagnetic(AFM)state.This discrepancy casts doubt on the validity of the 1k magnetic ordering of UN.Here,we investigate the crystal structure,high-pressure phase transitions,and dynamical and mechanical properties of UN in its 1k and 3k AFM ground states using density functional theory(DFT).Our results reveal that the undistorted 3k AFM state of Fm3m within the DFT+U+SOC scheme is more consistent with experimental results.The Hubbard U and spin-orbit coupling(SOC)are critical for accurately capturing the crystal structure,high-pressure structural phase transition,and dynamical properties of UN.In addition,we have identified a new high-pressure magnetic phase transition from the nonmagnetic(NM)phase of R3m to the P63/mmc AFM state.Electronic structure analysis reveals that the magnetic ordering in the ground state is primarily linked to variations in partial 5f orbital distributions.Our calculations provide valuable theoretical insights into the complex magnetic structures of a typical strongly correlated uranium-based compound.Moreover,they provide a framework for understanding other similar actinide systems.展开更多
Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic ...Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.展开更多
Antiferromagnetic(AFM)spintronics have sparked extensive research interest in the field of information storage due to the considerable advantages offered by antiferromagnets,including non-volatile data storage,higher ...Antiferromagnetic(AFM)spintronics have sparked extensive research interest in the field of information storage due to the considerable advantages offered by antiferromagnets,including non-volatile data storage,higher storage density,and accelerating data processing.However,the manipulation and detection of internal AFM order in antiferromagnets hinders their applications in spintronic devices.Here,we proposed a design idea for an AFM material that is self-assembled from one-dimensional(1D)ferromagnetic(FM)chains.To validate this idea,we screened a two-dimensional(2D)selfassembled CrBr_(2)antiferromagnet of an AFM semiconductor from a large amount of data.This 2D CrBr_(2)antiferromagnet is composed of 1D FM CrBr_(2)chains that are arranged in a staggered and parallel configuration.In this type of antiferromagnet,the write-data operation of information is achieved in 1D FM chains,followed by a self-assembly process driving the assembly of 1D FM chains into an antiferromagnet.These constituent 1D FM chains become decoupled by external perturbations,such as heat,pressure,strain,etc.,thereby realizing the read-data operation of information.We anticipate that this antiferromagnet,composed of 1D FM chains,can be realized not only in the 1D to 2D system,but also is expected to expand to 2D to three-dimensional(3D)system,and even 1D to 3D system.展开更多
The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific ...The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific configuration of applied magnetics fields and current and can persist up to 20 K,much higher than the Ne'el temperature(T_(N)≈1.9 K).Experiments and first-principles calculations suggest that the observed large negative MR is derived from a magnetic field that reconstructs the band structure and induces a Weyl point,which changes the carrier concentration.展开更多
The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic si...The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.展开更多
We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AF...We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AFM) transitions have been observed at T_(N1)~18.9 K, T_(N2)~7.0 K, and T_(N3)~3.1 K. Among them, the transitions at T_(N2) and T_(N3) represent the canted AFM orders with ferromagnetic components. As the magnetic field increases, the transition at T_(N3) is rapidly suppressed to disappearance. However, the transitions at T_(N1) and T_(N2) persist until high fields and their signatures can also be reflected in the resistivity and specific heat. Above the magnetic transition temperature T_(N1), the resistivity of EuBi_(2) increases linearly with temperature, exhibiting the strange-metal behavior. In the magnetically ordered region below T_(N1), EuBi_(2) exhibits the weak antilocalization(WAL) effect and large magnetoresistance(475% at 1.8 K and 14 T). It is suggested that the magnetic ordering significantly enhances the spin–orbital coupling interaction and induces the WAL effect.展开更多
The intrinsic antiferromagnetic topological insulators in the Mn-Bi-Te family,composed of superlattice-like MnBi_(2)Te_(4)/(Bi_(2)Te_(3))_(n)(n=0,1,2,3,...)layered structure,present intriguing states of matter such as...The intrinsic antiferromagnetic topological insulators in the Mn-Bi-Te family,composed of superlattice-like MnBi_(2)Te_(4)/(Bi_(2)Te_(3))_(n)(n=0,1,2,3,...)layered structure,present intriguing states of matter such as quantum anomalous Hall effect and the axion insulator.However,the surface state gap,which is the prerequisite for the observation of these states,remains elusive.Here by molecular beam epitaxy,we obtain two types of MnBi_(4)Te_(7)films with the exclusive Bi_(2)Te_(3)(BT)or MnBi_(2)Te_(4)(MBT)terminations.By scanning tunneling spectroscopy,the mass terms in the surface states are identified on both surface terminations.Experimental results reveal the existence of a hybridization gap of approximately 23 meV in surface states on the BT termination.This gap comes from the hybridization between the surface states and the spin-split states in the adjacent MBT layer.On the MBT termination,an exchange mass term of about 28±2 meV in surface states is identified by taking magnetic-field-dependent Landau level spectra as well as theoretical simulations.In addition,the mass term varies with the field in the film with a heavy BiMn doping level in the Mn layers.These findings demonstrate the existence of mass terms in surface states on both types of terminations in our epitaxial MnBi_(4)Te_(7)films investigated by local probes.展开更多
In this investigation,we delve into the interplay between strong interactions and intricate topological configurations,leading to emergent quantum states such as magnetic topological insulators.The crux of our researc...In this investigation,we delve into the interplay between strong interactions and intricate topological configurations,leading to emergent quantum states such as magnetic topological insulators.The crux of our research centers on elucidating how lattice symmetry modulates antiferromagnetic quantum Hall phenomena.Utilizing the spinful Harper-Hofstadter model enriched with a next-nearest-neighbor(NNN)hopping term,we discern a half-filling bandgap,paving the way for the manifestation of a quantum Hall insulator characterized by a Chern number,C=2.Upon integrating a checkerboardpatterned staggered potential(△)and the Hubbard interaction(U),the system exhibits complex dynamical behaviors.Marginal NNN hopping culminates in a Ne′el antiferromagnetic Mott insulator.In contrast,intensified hopping results in stripe antiferromagnetic configurations.Moreover,in the regime of limited NNN hopping,a C=1 Ne′el antiferromagnetic quantum Hall insulator emerges.A salient observation pertains to the manifestation of a C=1 antiferromagnetic quantum Hall insulator when spin-flip mechanisms are not offset by space group symmetries.These findings chart a pathway for further explorations into antiferromagnetic Quantum Hall States.展开更多
We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscop...We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscopic calculation, we show that the optical spin wave mode at the Brillouin zone center can acquire a small orbital magnetic moment, although it exhibits no magnetic moment from the Zeeman coupling. Our results are potentially applicable to intercalated van der Waals materials and twisted double-bilayer graphene.展开更多
Vanadium-based transition metal chalcogenides VmXn(X=S,Se,Te)with their distinctive quantum effects,tunable magnetism,spin-orbit coupling,and high carrier mobility are a valuable platform to explore the interplay betw...Vanadium-based transition metal chalcogenides VmXn(X=S,Se,Te)with their distinctive quantum effects,tunable magnetism,spin-orbit coupling,and high carrier mobility are a valuable platform to explore the interplay between magnetism and electronic correlations,especially with tunable structural phases and magnetic properties through stoichiometric variations,making them ideal candidates for advanced device applications.Here,we report the synthesis of high-quality V_(5+x)S_(8)single crystals with different concentrations of self-intercalated vanadium.V_(5+x)S_(8)crystals show an antiferromagnetic behavior and a spin-flop-like transition below TN of 30.6 K.The high-quality V_(5+x)S_(8)single crystals exhibit a large negative magnetoresistance of 12.3%at 2 K.Interestingly,V_(5+x)S_(8)crystals show an obvious low-temperature resistance upturn that gradually levels off with the increasing magnetic field,attributed to the Kondo effect arising from the interaction between conduction electrons and embedded vanadium magnetic impurities.With increasing V doping,the antiferromagnetic interactions intensify,weakening the coupling between the local moments and conduction electrons,which in turn lowers the Kondo temperature(TK).Furthermore,the anomalous Hall effect is observed in V5.73S8,with an anomalous Hall conductivity(AHC)of 50.46 W^(-1)·cm^(-1)and anomalous Hall angle of 0.73%at 2 K.Our findings offer valuable insights into the mechanisms of the Kondo effect and anomalous Hall effect in self-intercalated transition metal chalcogenides with complex magnetism and electronic correlation effects.展开更多
FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in F...FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in FeSe.FeSe is recognized as a prototypical platform for competing magnetic interactions,including Néel,stripe,and staggered antiferromagnetic coupling.However,the correlations between these magnetic orders and how they change with varying environmental conditions require further study.Here,we calculated the magnetic order of monolayer FeSe in three diferent environments:pure one,with slight lattice distortion,and on SrTiO_(3) substrate,by frst principles calculations.We fnd that in the calculated dispersion relation E(q)between the spin spiral energy E and spin spiral vector q of the monolayer FeSe structure,the stripe magnetic order M(π/2,π/2)has the lowest energy,and there is a fat E(q)between the wave vector X(π/2,0)and Néel magnetic order 2X(π,0),which are the degenerate E(q)states.The ground state of M and the highest density of states around 2X may be the reason for the competition of two magnetic orders.The slight lattice distortion does not alter the magnetic properties of monolayer FeSe.When monolayer FeSe is attached to the SrTiO_(3)substrate,the degenerate E(q)is still retained;meanwhile,the energy of the 2X(π,0)state is closer to the M state,which may be one of the reasons for the increase of superconducting temperature in FeSe/SrTiO_(3).展开更多
Motivated by the recent discovery of unconventional superconductivity around a magnetic quantum critical point in pressurized CeSb_(2),here we present a high-pressure study of an isostructural antiferromagnetic(AFM) S...Motivated by the recent discovery of unconventional superconductivity around a magnetic quantum critical point in pressurized CeSb_(2),here we present a high-pressure study of an isostructural antiferromagnetic(AFM) SmSb_(2) through electrical transport and synchrotron x-ray diffraction measurements.At P_(C)~2.5 GPa,we found a pressure-induced magnetic phase transition accompanied by a Cmca→P4/nmm structural phase transition.In the pristine AFM phase below P_(C),the AFM transition temperature of SmSb_(2) is insensitive to pressure;in the emergent magnetic phase above P_(C),however,the magnetic critical temperature increases rapidly with increasing pressure.In addition,at ambient pressure,the magnetoresistivity(MR) of SmSb_(2) increases suddenly upon cooling below the AFM transition temperature and presents linear nonsaturating behavior under high field at 2 K.With increasing pressure above P_(C),the MR behavior remains similar to that observed at ambient pressure,both in terms of temperature-and field-dependent MR.This leads us to argue an AFM-like state for SmSb_(2) above P_(C).Within the investigated pressure of up to 45.3 GPa and the temperature of down to 1.8 K,we found no signature of superconductivity in SmSb_(2).展开更多
Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor t...Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.展开更多
Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heise...Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the a-axis.CoTi2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic region.Although a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below TN.Both the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.展开更多
We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used ...We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.展开更多
The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structur...The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structures, the two ferromagneticlayers demonstrate in-phase and out-of-phase states, corresponding to acoustic and optical precession modes. Withinthis context, our study explores the spin pumping effect in Py/Ru/Py synthetic antiferromagnetic structures across differentmodes. The heightened magnetic damping resulting from the spin pumping effect in the in-phase state initially decreaseswith increasing Py thickness before stabilizing. Conversely, in the out-of-phase state, the amplified damping exceeds thatof the in-phase state, suggesting a greater spin relaxation within this configuration, which demonstrates sensitivity to alterationsin static exchange interactions. These findings contribute to advancing the application of synthetic antiferromagneticstructures in magnonic devices.展开更多
文摘High-quality antiferromagnetic(AFM)θ-phase manganese nitride(MnN)films were successfully grown on MgO(001)substrates by plasma-assisted molecular beam epitaxy.Structural analysis confirms the high-quality MnN film has a tetragonal distortion with a c/a ratio of~0.98.The film exhibits exceptional stability in both aqueous and ambient conditions,which is a crucial factor for practical applications.Electrical transport reveals its metallic behavior with an upturn at low temperatures,which could be attributed to the Kondo effect originated from nitrogen vacancy-induced magnetic impurities.Room temperature exchange bias has been demonstrated in a MnN/CoFeB heterostructure,verifying the AFM ordering of MnN.Considering its high Néel temperature~650 K,superior stability,and low-cost,this work highlights the epitaxial MnN films as a promising candidate for AFM spintronic applications.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1402203)the National Natural Science Foundations of China(Grant Nos.12174065 and 12104424)the Shanghai Municipal Science and Technology(Grant No.2019SHZDZX01)。
文摘In this work,Ga-doped Ce RhIn_(5) single crystals are grown by In/Ga flux method.Single-crystal X-ray diffraction,magnetic susceptibility,specific heat,and neutron diffraction measurements are utilized to characterize the sample quality and the antiferromagnetic transition temperature T_(N).By substituting In with Ga,T_(N) is slightly decreased,but the antiferromagnetic transition peaks in magnetic susceptibility and specific heat measurements are obviously broadened by external field along c-axis.By comparing with Zn-doped Ce RhIn_(5),it can be concluded that T_(N) is dominated by electron density,and the stiffness of antiferromagnetic transition is obviously reduced by Ga substitution.The substitution effects of Ga are possibly caused by forming heterogeneous local structures,which avoids quantum critical point,superconductivity,and non-Fermi liquid states.Investigations on Gadoped Ce RhIn_(5) help to comprehend the chemical substitution effects in Ce RhIn_(5),and the interaction between heterogeneous structure and long-range antiferromagnetic states.
基金supported by the National Key Projects for Research and Development of China(Grant Nos.2021YFA1400400 and 2024YFA1408104)the National Natural Science Foundation of China(Grant Nos.12434005,12374137,and 92165205).
文摘We investigate the origin of the 1/3 magnetization plateau in the S=1/2 kagome antiferromagnetic Heisenberg model using the variational Monte Carlo and exact diagonalization methods,to account for the recent experimental observations in YCu_(3)(OH)_(6+x)Br_(3-x)and YCu_(3)(OD)_(6+x)Br_(3-x).We identify three degenerate valencebond-solid(VBS)states forming a√3×√3 unit cell.These states exhibit David-star patterns in the spin moment distribution with only two fractional values-1/3 and 2/3,and are related through translational transformations.While the spin correlations in these VBS states are found to be short-range,resembling a quantum spin liquid,we show that they have a vanishing topological entanglement entropy and thus are topologically trivial many-body states.Our theoretical results provide strong evidence that the 1/3 magnetization plateau observed in recent experiments arises from these√3×√3 VBS states with fractional spin moments.
基金supported by the Natural Science Foundation of the Xinjiang Uygur Autonomous Region(2024D01E30)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0880000)+1 种基金the Open Fund of the Anhui Key Laboratory of Photonic Materials and Devices(AHKL2024KF02)the National Natural Science Foundation of China(22475234,22335007,22193044 and 22361132544).
文摘Multifunctional semiconductors play an important role in developing advanced photoelectric technologies.In this work,based on an octahedral replacement strategy in chalcogenides,a new selenide semiconductor NaMn_(3)Ga_(3)Se_(8)was rationally designed,and synthesized by the flux method.The compound crystallizes in the noncentrosymmetric(NCS)P_(6)space group,and is composed of unique prismatic[NaSe_(6)],octahedral[MnSe_(6)]and tetrahedral[GaSe_(4)]motifs,inheriting the stable three-dimensional framework built by the octahedral and tetrahedral units in the A^(Ⅰ)Mg_(3)^(Ⅱ)C_(3)^(Ⅲ)Q_(8)^(Ⅵ)family.NaMn_(3)Ga_(3)Se_(8)shows the largest known secondary nonlinear optical(NLO)response of~2.1×AgGaS_(2)(AGS)in the A^(Ⅰ)Mg_(3)^(Ⅱ)C_(3)^(Ⅲ)Q_(8)^(Ⅵ)family,and a high laser-induced damage threshold of~3.0×AGS.Meanwhile,the introduction of Mn2t with unpaired 3d electrons induces a strong red emission band(685–805 nm)under the excitation source of 496 nm,as well as a paramagnetic to antiferromagnetic(AFM)transition at 7.3 K.The results confirm that NaMn_(3)Ga_(3)Se_(8)possesses multifunctional features including significant NLO response,fluorescence emission and AFM properties,and illustrate that replacing octahedral units with approaching size and geometry(like[MgSe_(6)]and[MnSe_(6)])could be a feasible way to develop multifunctional chalcogenides.
基金supported by the National Natural Science Foundation of China(Grant Nos.12204482 and U2430211)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2020L0537)the Fundamental Research Program of Shanxi Province(Grant No.202103021224250)the Hainan Provincial Natural Science Foundation of China(Grant No.225MS076).
文摘The ground-state magnetic ordering of uranium mononitride(UN)remains a contentious topic due to the unexpected lack of crystallographic distortion in the traditionally accepted 1k antiferromagnetic(AFM)state.This discrepancy casts doubt on the validity of the 1k magnetic ordering of UN.Here,we investigate the crystal structure,high-pressure phase transitions,and dynamical and mechanical properties of UN in its 1k and 3k AFM ground states using density functional theory(DFT).Our results reveal that the undistorted 3k AFM state of Fm3m within the DFT+U+SOC scheme is more consistent with experimental results.The Hubbard U and spin-orbit coupling(SOC)are critical for accurately capturing the crystal structure,high-pressure structural phase transition,and dynamical properties of UN.In addition,we have identified a new high-pressure magnetic phase transition from the nonmagnetic(NM)phase of R3m to the P63/mmc AFM state.Electronic structure analysis reveals that the magnetic ordering in the ground state is primarily linked to variations in partial 5f orbital distributions.Our calculations provide valuable theoretical insights into the complex magnetic structures of a typical strongly correlated uranium-based compound.Moreover,they provide a framework for understanding other similar actinide systems.
基金Project supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C01053)the Key Research and Development Program of Zhejiang Province(Grant No.2021C01039)+1 种基金the National Natural Science Foundation of China(Grant No.62293493)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ21A050001)。
文摘Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12435001,12304006,and 12404265)the Natural Science Foundation of Shanghai,China(Grant No.23JC1401400)+1 种基金the Fundamental Research Funds for the Central Universities of East China University,the Natural Science Foundation of WIUCAS(Grant No.WIUCASQD2023004)the Natural Science Foundation of Wenzhou(Grant No.L2023005)。
文摘Antiferromagnetic(AFM)spintronics have sparked extensive research interest in the field of information storage due to the considerable advantages offered by antiferromagnets,including non-volatile data storage,higher storage density,and accelerating data processing.However,the manipulation and detection of internal AFM order in antiferromagnets hinders their applications in spintronic devices.Here,we proposed a design idea for an AFM material that is self-assembled from one-dimensional(1D)ferromagnetic(FM)chains.To validate this idea,we screened a two-dimensional(2D)selfassembled CrBr_(2)antiferromagnet of an AFM semiconductor from a large amount of data.This 2D CrBr_(2)antiferromagnet is composed of 1D FM CrBr_(2)chains that are arranged in a staggered and parallel configuration.In this type of antiferromagnet,the write-data operation of information is achieved in 1D FM chains,followed by a self-assembly process driving the assembly of 1D FM chains into an antiferromagnet.These constituent 1D FM chains become decoupled by external perturbations,such as heat,pressure,strain,etc.,thereby realizing the read-data operation of information.We anticipate that this antiferromagnet,composed of 1D FM chains,can be realized not only in the 1D to 2D system,but also is expected to expand to 2D to three-dimensional(3D)system,and even 1D to 3D system.
基金financially supported by the National Key R&D Program of China(No.2022YFA1402600)the National Natural Science Foundation of China(Nos.12304150 and 52161135108)support by the National Science Centre(Poland)(No.2021/40/Q/ST5/00066)。
文摘The angular dependence of magnetoresistance(MR)in antiferromagnetic half-Heusler HoAuSn single crystals has been systematically studied.Negative MR,as large as~99%,is observed at 9 T,is not restricted to the specific configuration of applied magnetics fields and current and can persist up to 20 K,much higher than the Ne'el temperature(T_(N)≈1.9 K).Experiments and first-principles calculations suggest that the observed large negative MR is derived from a magnetic field that reconstructs the band structure and induces a Weyl point,which changes the carrier concentration.
基金supported by the National Natural Science Foundation of China (Grant No. 12174382)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDB0460000 and XDB28000000)the Innovation Program for Quantum Science and Technology (Grant Nos. 2024ZD0300104 and 2021ZD0302600)。
文摘The competition between dimensionality and ordering in multiferroic materials is of great interest for both fundamental physics and potential applications. Combining first-principles calculations with micromagnetic simulations, we investigate recently synthesized ultrathin perovskite bismuth ferrite(BFO) films. Our numerical results reveal that, at the monolayer limit, the ferroelectricity of BFO is missing because the octahedral distortions are constrained. However, the monolayer bismuth ferrite is a topological antiferromagnetic metal with tunable bimeron magnetic structure. The dual topologically non-trivial characteristics make monolayer bismuth ferrite a multifunctional building block in future spintronic devices.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12474098, 12274388, 12174361, 12404191, 52102333, 12404043, and 12204004)the Natural Science Foundation of Anhui Province (Grant No. 2408085QA024)。
文摘We report the magnetic and transport properties of EuBi_(2) single crystal. EuBi_(2) exhibits complex magnetic behavior at low temperatures. In both the in-plane and out-of-plane directions, three antiferromagnetic(AFM) transitions have been observed at T_(N1)~18.9 K, T_(N2)~7.0 K, and T_(N3)~3.1 K. Among them, the transitions at T_(N2) and T_(N3) represent the canted AFM orders with ferromagnetic components. As the magnetic field increases, the transition at T_(N3) is rapidly suppressed to disappearance. However, the transitions at T_(N1) and T_(N2) persist until high fields and their signatures can also be reflected in the resistivity and specific heat. Above the magnetic transition temperature T_(N1), the resistivity of EuBi_(2) increases linearly with temperature, exhibiting the strange-metal behavior. In the magnetically ordered region below T_(N1), EuBi_(2) exhibits the weak antilocalization(WAL) effect and large magnetoresistance(475% at 1.8 K and 14 T). It is suggested that the magnetic ordering significantly enhances the spin–orbital coupling interaction and induces the WAL effect.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1403102)the National Natural Science Foundation of China(Grant Nos.12474478,92065102,and 61804056).
文摘The intrinsic antiferromagnetic topological insulators in the Mn-Bi-Te family,composed of superlattice-like MnBi_(2)Te_(4)/(Bi_(2)Te_(3))_(n)(n=0,1,2,3,...)layered structure,present intriguing states of matter such as quantum anomalous Hall effect and the axion insulator.However,the surface state gap,which is the prerequisite for the observation of these states,remains elusive.Here by molecular beam epitaxy,we obtain two types of MnBi_(4)Te_(7)films with the exclusive Bi_(2)Te_(3)(BT)or MnBi_(2)Te_(4)(MBT)terminations.By scanning tunneling spectroscopy,the mass terms in the surface states are identified on both surface terminations.Experimental results reveal the existence of a hybridization gap of approximately 23 meV in surface states on the BT termination.This gap comes from the hybridization between the surface states and the spin-split states in the adjacent MBT layer.On the MBT termination,an exchange mass term of about 28±2 meV in surface states is identified by taking magnetic-field-dependent Landau level spectra as well as theoretical simulations.In addition,the mass term varies with the field in the film with a heavy BiMn doping level in the Mn layers.These findings demonstrate the existence of mass terms in surface states on both types of terminations in our epitaxial MnBi_(4)Te_(7)films investigated by local probes.
文摘In this investigation,we delve into the interplay between strong interactions and intricate topological configurations,leading to emergent quantum states such as magnetic topological insulators.The crux of our research centers on elucidating how lattice symmetry modulates antiferromagnetic quantum Hall phenomena.Utilizing the spinful Harper-Hofstadter model enriched with a next-nearest-neighbor(NNN)hopping term,we discern a half-filling bandgap,paving the way for the manifestation of a quantum Hall insulator characterized by a Chern number,C=2.Upon integrating a checkerboardpatterned staggered potential(△)and the Hubbard interaction(U),the system exhibits complex dynamical behaviors.Marginal NNN hopping culminates in a Ne′el antiferromagnetic Mott insulator.In contrast,intensified hopping results in stripe antiferromagnetic configurations.Moreover,in the regime of limited NNN hopping,a C=1 Ne′el antiferromagnetic quantum Hall insulator emerges.A salient observation pertains to the manifestation of a C=1 antiferromagnetic quantum Hall insulator when spin-flip mechanisms are not offset by space group symmetries.These findings chart a pathway for further explorations into antiferromagnetic Quantum Hall States.
基金Project supported by the National Key R&D Program of China (Grant No. 2022YFA1403800)the National Natural Science Foundation of China (Grant Nos. 12250008 and 12188101)+1 种基金the Project for Young Scientists in Basic Research (Grant No. YSBR-059)performed in part at the Aspen Center for Physics, supported by the National Natural Science Foundation of China (Grant No. PHY2210452)。
文摘We theoretically study the effect of a uniform orbital magnetic field on spin waves in a triangular lattice tetrahedral antiferromagnetic insulator without spin–orbit coupling. Through symmetry analysis and microscopic calculation, we show that the optical spin wave mode at the Brillouin zone center can acquire a small orbital magnetic moment, although it exhibits no magnetic moment from the Zeeman coupling. Our results are potentially applicable to intercalated van der Waals materials and twisted double-bilayer graphene.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1204100)the National Natural Science Foundation of China(Grant Nos.62488201 and 1240041502)+2 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Chinese Academy of Sciences(Grant No.XDB33030100)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700).
文摘Vanadium-based transition metal chalcogenides VmXn(X=S,Se,Te)with their distinctive quantum effects,tunable magnetism,spin-orbit coupling,and high carrier mobility are a valuable platform to explore the interplay between magnetism and electronic correlations,especially with tunable structural phases and magnetic properties through stoichiometric variations,making them ideal candidates for advanced device applications.Here,we report the synthesis of high-quality V_(5+x)S_(8)single crystals with different concentrations of self-intercalated vanadium.V_(5+x)S_(8)crystals show an antiferromagnetic behavior and a spin-flop-like transition below TN of 30.6 K.The high-quality V_(5+x)S_(8)single crystals exhibit a large negative magnetoresistance of 12.3%at 2 K.Interestingly,V_(5+x)S_(8)crystals show an obvious low-temperature resistance upturn that gradually levels off with the increasing magnetic field,attributed to the Kondo effect arising from the interaction between conduction electrons and embedded vanadium magnetic impurities.With increasing V doping,the antiferromagnetic interactions intensify,weakening the coupling between the local moments and conduction electrons,which in turn lowers the Kondo temperature(TK).Furthermore,the anomalous Hall effect is observed in V5.73S8,with an anomalous Hall conductivity(AHC)of 50.46 W^(-1)·cm^(-1)and anomalous Hall angle of 0.73%at 2 K.Our findings offer valuable insights into the mechanisms of the Kondo effect and anomalous Hall effect in self-intercalated transition metal chalcogenides with complex magnetism and electronic correlation effects.
基金supported by the National Natural Science Foundation of China(Grant Nos.11204131 and 11974181)。
文摘FeSe is an Fe-based paramagnetic superconductor with the simplest structure.The competition between the Néel and stripe magnetic orders is believed to be one of the reasons for the absence of magnetic orders in FeSe.FeSe is recognized as a prototypical platform for competing magnetic interactions,including Néel,stripe,and staggered antiferromagnetic coupling.However,the correlations between these magnetic orders and how they change with varying environmental conditions require further study.Here,we calculated the magnetic order of monolayer FeSe in three diferent environments:pure one,with slight lattice distortion,and on SrTiO_(3) substrate,by frst principles calculations.We fnd that in the calculated dispersion relation E(q)between the spin spiral energy E and spin spiral vector q of the monolayer FeSe structure,the stripe magnetic order M(π/2,π/2)has the lowest energy,and there is a fat E(q)between the wave vector X(π/2,0)and Néel magnetic order 2X(π,0),which are the degenerate E(q)states.The ground state of M and the highest density of states around 2X may be the reason for the competition of two magnetic orders.The slight lattice distortion does not alter the magnetic properties of monolayer FeSe.When monolayer FeSe is attached to the SrTiO_(3)substrate,the degenerate E(q)is still retained;meanwhile,the energy of the 2X(π,0)state is closer to the M state,which may be one of the reasons for the increase of superconducting temperature in FeSe/SrTiO_(3).
基金Project supported by the National Key Research and Development Program of China (Grant Nos. 2023YFA1406102 and 2022YFA1602603)the National Natural Science Foundation of China (Grant Nos. 12374049 and 12174395)+2 种基金the China Postdoctoral Science Foundation (Grant No. 2023M743542)Hefei Institutes of Physical Science,Chinese Academy of Sciences the Director’s Fundation of (Grant No. YZJJ2024QN41)the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures (Grant No. JZHKYPT-2021-08)。
文摘Motivated by the recent discovery of unconventional superconductivity around a magnetic quantum critical point in pressurized CeSb_(2),here we present a high-pressure study of an isostructural antiferromagnetic(AFM) SmSb_(2) through electrical transport and synchrotron x-ray diffraction measurements.At P_(C)~2.5 GPa,we found a pressure-induced magnetic phase transition accompanied by a Cmca→P4/nmm structural phase transition.In the pristine AFM phase below P_(C),the AFM transition temperature of SmSb_(2) is insensitive to pressure;in the emergent magnetic phase above P_(C),however,the magnetic critical temperature increases rapidly with increasing pressure.In addition,at ambient pressure,the magnetoresistivity(MR) of SmSb_(2) increases suddenly upon cooling below the AFM transition temperature and presents linear nonsaturating behavior under high field at 2 K.With increasing pressure above P_(C),the MR behavior remains similar to that observed at ambient pressure,both in terms of temperature-and field-dependent MR.This leads us to argue an AFM-like state for SmSb_(2) above P_(C).Within the investigated pressure of up to 45.3 GPa and the temperature of down to 1.8 K,we found no signature of superconductivity in SmSb_(2).
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFA1403202)the National Natural Science Foundation of China(Grant Nos.NSFC-12074335,11974095,5177115,11974095,and 12188101)the Natural Science Foundation of Shaanxi Province of China(Grant No.2022JM-028).
文摘Intercalated transition metal dichalcogenides(TMDCs)attract much attention due to their rich properties and potential applications.In this article,we grew successfully high-quality V_(1/3)TaS_(2) crystals by a vapor transport method.We measured the magnetization,longitudinal resistivityρxx(T,H),Hall resistivityρxy(T,H),as well as performed calculations of the electronic band structure.It was found that V_(1/3)TaS_(2) is an A-type antiferromagnet with the Neel temperature T_(N)=6.20 K,and exhibits a negative magnetoresistance(MR)near T_(N).Both band structure calculations and Hall resistivity measurements demonstrated it is a magnetic semimetal.
基金supported by the National Natural Science Foundation of China (Grant No. 52372003)the Funds from Beijing National Laboratory for Condensed Matter Physics
文摘Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the a-axis.CoTi2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic region.Although a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below TN.Both the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.
基金Project supported by the Natural Science Basic Research Program of Shaanxi(Program Nos.2023KJXX-064 and 2021JQ-748)the National Natural Science Foundation of China(Grant Nos.11804213 and 12174238)Scientific Research Foundation of Shaanxi University of Technology(Grant No.SLGRCQD2006).
文摘We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.
基金National Key Research and De-velopment Program of China(Grant No.2023YFA1406603)the National Natural Science Foundation of China(Grant Nos.52071079,12274071,12374112,and T2394473)Jiangsu Funding Program for Excellent Postdoctoral Talent(Grant No.2023ZB491).
文摘The spin pumping effect in magnetic heterostructures and multilayers is a highly effective method for the generationand transmission of spin currents. In the increasingly prominent synthetic antiferromagnetic structures, the two ferromagneticlayers demonstrate in-phase and out-of-phase states, corresponding to acoustic and optical precession modes. Withinthis context, our study explores the spin pumping effect in Py/Ru/Py synthetic antiferromagnetic structures across differentmodes. The heightened magnetic damping resulting from the spin pumping effect in the in-phase state initially decreaseswith increasing Py thickness before stabilizing. Conversely, in the out-of-phase state, the amplified damping exceeds thatof the in-phase state, suggesting a greater spin relaxation within this configuration, which demonstrates sensitivity to alterationsin static exchange interactions. These findings contribute to advancing the application of synthetic antiferromagneticstructures in magnonic devices.
