We report the crystal growth of a new hole-doped iron-based superconductor Ba(Fe_(0.875)Ti_(0.125))_(2)As_(2)by substituting Ti on the Fe site.The crystals are accidentally obtained in trying to grow Ni doped Ba_(2)Ti...We report the crystal growth of a new hole-doped iron-based superconductor Ba(Fe_(0.875)Ti_(0.125))_(2)As_(2)by substituting Ti on the Fe site.The crystals are accidentally obtained in trying to grow Ni doped Ba_(2)Ti_(2)Fe_(2)As_(4)O.After annealing at 500℃ in vacuum for one week,superconductivity is observed with zero resistance at T_(c0)≈17.5 K,and about 20%diamagnetic volume down to 2 K.While both the small anisotropy of superconductivity and the temperature dependence of normal state resistivity are akin to the electron doped 122-type compounds,the Hall coefficient is positive and similar to the case in hole-doped Ba_(0.9)K_(0.1)Fe_(2)As2.The density functional theory calculations suggest dominated hole pockets contributed by Fe/Ti 3d orbitals.Therefore,the Ba(Fe_(1-x)Ti_(x))_(2)As_(2)system provides a new platform to study the superconductivity with hole doping on the Fe site of iron-based superconductors.展开更多
Topological superconductor islands are thought to be the building blocks of topological quantum bits.We produced single-crystalline VSi_(x)islands with well-defined side facets and island size more than 200nm using mo...Topological superconductor islands are thought to be the building blocks of topological quantum bits.We produced single-crystalline VSi_(x)islands with well-defined side facets and island size more than 200nm using molecular beam epitaxy on Si substrate heated to 950℃throughout the growth process.By means of scanning tunneling spectroscopy,we revealed dynamical Coulomb blockade and superconductivity on isolated islands and on islands being connected by superconducting wetting layer respectively.Bi_(2)Te_(3)films were further deposited on VSi_(x)islands.Robust and homogenous proximity effect induced superconductivity was observed on various facets of the Bi_(2)Te_(3)/VSi_(x)hetero-nanostructure.Furthermore,our high-resolution spectroscopy identified Bosonic mode excitations on the topological superconductor islands.These results may establish a playground for the vortex Majorana islands.展开更多
The kagome lattice,characterized by a hexagonal arrangement of corner-sharing equilateral triangles,has garnered significant attention as a fascinating quantum material system that hosts exotic magnetic and electronic...The kagome lattice,characterized by a hexagonal arrangement of corner-sharing equilateral triangles,has garnered significant attention as a fascinating quantum material system that hosts exotic magnetic and electronic properties.The identification and characterization of this class of materials are critical for advancing our understanding of their role in emergent phenomena such as superconductivity.In this study,we developed a high-throughput screening framework for the systematic identification and classification of superconducting materials with kagome lattices,integrating them into established materials databases.Leveraging the Materials Project(MP)database and the MDR Super Con dataset,we analyzed over 150000 inorganic compounds and cross-referenced 26000 known superconductors.Using geometry-based structural modeling and experimental validation,we identified 129 kagome superconductors belonging to 17 distinct structural families,many of which had not previously been recognized as kagome systems.The materials are further classified into three categories in terms of topological flat bands,clean band structures,and coexisting magnetic or charge density wave(CDW)orderings.Based on these results,we established a database comprising 129 kagome superconductors,including the detailed crystallographic,electronic,and superconducting properties of these materials.展开更多
Iron-based superconductors(FeSCs)feature a complex phase diagram,and their diverse cleavage terminations offer a versatile platform for modulating surface electronic states and investigating the underlying superconduc...Iron-based superconductors(FeSCs)feature a complex phase diagram,and their diverse cleavage terminations offer a versatile platform for modulating surface electronic states and investigating the underlying superconducting mechanisms.In this study,we explore the surface modulation of KCa_(2)Fe_(4)As_(4)F_(2)using scanning tunneling microscopy/spectroscopy.Cryogenically cleaved surfaces reveal multiple configurations,including√2×√2 reconstruction,1×2 and 1×3 stripes,as well as nanoscale vacancies.Reducing potassium coverage induces hole doping,which shifts the density of states peak toward the Fermi level and suppresses the superconducting gap from 4.8 meV to 3.2 meV.This behavior is reminiscent of the Van Hove singularity observed in hole-doped 122-type FeSCs.The band structure does not undergo a simple rigid shift,and the evolution of superconductivity can be attributed to the interplay between surface carriers and electronic correlations.Additionally,a V-shaped gap is observed at a unique location preserving the FeAs bilayer structure,where interlayer coupling effects are likely involved.The diversity of surface structures and electronic states in K12442 enhances our understanding of FeSCs and facilitates the modulation and application of FeAs superconducting layers.展开更多
The discovery of high-temperature superconducting materials holds great significance for human industry and daily life.In recent years,research on predicting superconducting transition temperatures using artificial in...The discovery of high-temperature superconducting materials holds great significance for human industry and daily life.In recent years,research on predicting superconducting transition temperatures using artificial intelligence(AI)has gained popularity,with most of these tools claiming to achieve remarkable accuracy.However,the lack of widely accepted benchmark datasets in this field has severely hindered fair comparisons between different AI algorithms and impeded further advancement of these methods.In this work,we present HTSC-2025,an ambient-pressure high-temperature superconducting benchmark dataset.This comprehensive compilation encompasses theoretically predicted superconducting materials discovered by theoretical physicists from 2023 to 2025 based on BCS superconductivity theory,including the renowned X_(2)YH_(6)system,perovskite MXH_(3)system,M_(3)H_(8)system,cage-like BCN-doped metal atomic systems derived from LaH_(10)structural evolution,and two-dimensional honeycomb-structured systems evolving from MgB_(2).In addition,we note a range of approaches inspired by physical intuition for designing high-temperature superconductors,such as hole doping,the introduction of light elements to form strong covalent bonds,and the tuning of spin-orbit coupling.The dataset presented in this paper is openly available at Science DB.The HTSC-2025 benchmark has been open-sourced on Hugging Face at https://huggingface.co/datasets/xiao-qi/HTSC-2025 and will be continuously updated,while the Electronic Laboratory for Material Science platform is available at https://in.iphy.ac.cn/eln/link.html#/124/V2s4.展开更多
Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metalli...Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.展开更多
Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applicat...Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.展开更多
Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.B...Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.展开更多
The discovery of new superconducting materials,particularly those exhibiting high critical temperature(Tc),has been a vibrant area of study within the field of condensed matter physics.Conventional approaches primaril...The discovery of new superconducting materials,particularly those exhibiting high critical temperature(Tc),has been a vibrant area of study within the field of condensed matter physics.Conventional approaches primarily rely on physical intuition to search for potential superconductors within the existing databases.However,the known materials only scratch the surface of the extensive array of possibilities within the realm of materials.展开更多
The interplay between 2a_(0)×2a_(0)charge density wave(CDW),nematicity and superconductivity in AV_(3)Sb_(5)(A=K,Rb,Cs)compounds gives rise to a rich landscape of intriguing physical phenomena.In addition to the ...The interplay between 2a_(0)×2a_(0)charge density wave(CDW),nematicity and superconductivity in AV_(3)Sb_(5)(A=K,Rb,Cs)compounds gives rise to a rich landscape of intriguing physical phenomena.In addition to the 2a_(0)×2a_(0)CDW,a unidirectional 4a_(0)stripe CDW is also observed on the Sb surface of RbV3Sb5and CsV3Sb5.However,reports of stripe-like CDWs in KV3Sb5have been limited.Here,we report the first observation of a long-range unidirectional stripe order with a 6a_(0)modulation period on the Sb surface of KV_(3)Sb_(5),coexisting with the 2a_(0)×2a_(0)CDW.Notably,the intensity of the6a_(0)stripes in STM topographies exhibits pronounced contrast reversal between opposite bias voltages.Additionally,the wave vector of the 6a_(0)modulation shows no energy-dependent dispersion,confirming its CDW origin.Furthermore,the6a_(0)CDW is robust under a 7 T out-of-plane magnetic field and persists over a temperature range from 215 mK to 720 mK.These results provide compelling evidence for the emergence of a long-range unidirectional CDW in KV_(3)Sb_(5).展开更多
The kagome lattice,naturally encompassing Dirac fermions,flat bands,and van Hove singularities,tends to intertwine exotic electronic states.Revealing the characteristics of its Fermi surface will help clarify the natu...The kagome lattice,naturally encompassing Dirac fermions,flat bands,and van Hove singularities,tends to intertwine exotic electronic states.Revealing the characteristics of its Fermi surface will help clarify the nature of the complex quantum phenomena in kagome material.Here we report the Fermi surface properties of the novel kagome metal CsTi_(3)Bi_(5)by the de Haas-van Alphen oscillations.The observed oscillations are clear and consist of six principal frequencies ranging from 214 T to 1013 T.The angular dependence of the frequency implies a quasi-two-dimensional electronic structure.In addition,the geometry phase corresponding to 281 T,determined by direct Lifshitz-Kosevich formula fitting,yields a value close toπ,which may indicate a band structure with nontrivial topological property.These results underscore the potential of CsTi_(3)Bi_(5)as a promising platform to explore the interplay between topological order,electronic nematicity,and superconductivity.展开更多
The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the ...The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the analysis. By using the SO-FDTD method, the transmission spectrum is obtained and its characteristics are investigated for different thicknesses of superconductor layers and dielectric layers, from which a stop band starting from zero frequency can be apparently observed. The relation between this low-frequency stop band and relative temperature, and also the London penetration depth at a superconductor temperature of zero degree are discussed, separately. The low-frequency stop band properties of superconductor-dielectric superlattice thus are well disclosed.展开更多
We investigate the topological properties of twisted bilayer superconductors with different even-parity pairings in each layer.In the presence of spin-orbit coupling,the Hamiltonian is mapped into an effective odd-par...We investigate the topological properties of twisted bilayer superconductors with different even-parity pairings in each layer.In the presence of spin-orbit coupling,the Hamiltonian is mapped into an effective odd-parity superconductor.Based on this,we deduce the topological properties by examining the relative configuration between Fermi surface and Dirac pairing node.We show that mixed Rashba and Dresselhaus spin-orbit coupling and anisotropic hopping terms,which break the C_(4)symmetry of the Fermi surface,can induce first-order topological superconductors with non-zero bulk Chern number.This provides a versatile way to control the topological phases of bilayer superconductors by adjusting the twisted angle and chemical potential.We demonstrate our results using a typical twisted angle of 53.13°,at which the translation symmetry is restored and the Chern number and edge state are calculated using the Moir′e momentum.展开更多
Using a very useful quantity in physics and chemistry,the electronegativity,we have found that for nearly 70 high-Tc oxide superconductors(HTOS),the average electronegativity is in a narrow range 2.5-2.7.The differenc...Using a very useful quantity in physics and chemistry,the electronegativity,we have found that for nearly 70 high-Tc oxide superconductors(HTOS),the average electronegativity is in a narrow range 2.5-2.7.The difference of bond character between the HTOS and the conventional superconductors has been discussed.Finally,two categories of superconductors in terms of the group average electronegativity are suggested.展开更多
Solving the Bogoliubov-de Gennes equation, the energy levels of bound statesare obtained in the ferromagnetic superconductor. The Josephson currents in a ferromagneticsuperconductor/Insulator/d-wave superconductor jun...Solving the Bogoliubov-de Gennes equation, the energy levels of bound statesare obtained in the ferromagnetic superconductor. The Josephson currents in a ferromagneticsuperconductor/Insulator/d-wave superconductor junction are calculated as a function of the exchangefield, temperature, and insulating barrier strength. It is found that the Josephson criticalcurrent is always suppressed by the presence of exchange Geld h and depends on crystalline axisorientation of d-wave superconductor.展开更多
We review several recent theoretical and experimental results in the study of superconductor hybrids. This includes the recent experimental advances in the study of superconducting beamsplitters as well as more advanc...We review several recent theoretical and experimental results in the study of superconductor hybrids. This includes the recent experimental advances in the study of superconducting beamsplitters as well as more advanced superconductor hybrid systems including ferromagnets or Majorana fermions. In the same manner, theoretical studies have revealed that such superconductor hybrid systems pave the way towards electronic generation and detection of entanglement as well as possible use cases in quantum computing. We will review the aspects in detail and illustrate the possible next steps to be taken.展开更多
An international research team consisting of scientists from the Institute of Physics(IOP),Chinese Academy of Sciences in Beijing,the University of Maryland(UMD),and the Lawrence Berkeley National Laboratory(LBNL)has ...An international research team consisting of scientists from the Institute of Physics(IOP),Chinese Academy of Sciences in Beijing,the University of Maryland(UMD),and the Lawrence Berkeley National Laboratory(LBNL)has captured experimental evidence which sheds light on the mechanism of high temperature superconductivity in the so-called cuprate(copper oxide)superconductors,which were first discovered in 1986.展开更多
A dream long held by physicists has been to raise the critical temperature(Tc)—the temperature below which the material exhibits no electrical resistance—of a superconductor to room temperature.The most recent excit...A dream long held by physicists has been to raise the critical temperature(Tc)—the temperature below which the material exhibits no electrical resistance—of a superconductor to room temperature.The most recent excitement in that regard has centered on rare-earth superhydrides,of which LaH10 at 190 GPa has a remarkably high Tc of 260 K.展开更多
Although it was proposedmany years ago that compressed hydrogen should be a high-temperature superconductor,the goal of room-temperature superconductivity has so far remained out of reach.However,the successful synthe...Although it was proposedmany years ago that compressed hydrogen should be a high-temperature superconductor,the goal of room-temperature superconductivity has so far remained out of reach.However,the successful synthesis of the theoretically predicted hydrides H3S and LaH10 with high superconducting transition temperatures TC provides clear guidance for achieving this goal.The existence of these superconducting hydrides also confirms the utility of theoretical predictions in finding high-TC superconductors.To date,numerous hydrideshave been studied theoretically or experimentally,especially binary hydrides.Interestingly,some of them exhibit superconductivity above 200 K.To gain insight into these high-TC hydrides(>200 K)and facilitate further research,we summarize their crystal structures,bonding features,and electronic properties,as well as their superconductingmechanism.Based on hydrogen structuralmotifs,covalentH3Swith isolated hydrogen and several clathrate superhydrides(LaH10,YH9,and CaH6)are highlighted.Other predicted hydrides with various H-cages and two-dimensional H motifs are also discussed.Finally,we present a systematic discussion of the common features,current problems,and future challenges of these high-TC hydrides.展开更多
基金supported by the National Key R&D Program of China(Grant Nos.2023YFA1406100,2022YFA1403800,2022YFA1403400,and 2021YFA1400400)the National Natural Science Foundation of China(Grant Nos.12274444 and 12574165)+1 种基金the Chinese Academy of Sciences(Grant No.XDB25000000)financial support from HBNI-RRCAT。
文摘We report the crystal growth of a new hole-doped iron-based superconductor Ba(Fe_(0.875)Ti_(0.125))_(2)As_(2)by substituting Ti on the Fe site.The crystals are accidentally obtained in trying to grow Ni doped Ba_(2)Ti_(2)Fe_(2)As_(4)O.After annealing at 500℃ in vacuum for one week,superconductivity is observed with zero resistance at T_(c0)≈17.5 K,and about 20%diamagnetic volume down to 2 K.While both the small anisotropy of superconductivity and the temperature dependence of normal state resistivity are akin to the electron doped 122-type compounds,the Hall coefficient is positive and similar to the case in hole-doped Ba_(0.9)K_(0.1)Fe_(2)As2.The density functional theory calculations suggest dominated hole pockets contributed by Fe/Ti 3d orbitals.Therefore,the Ba(Fe_(1-x)Ti_(x))_(2)As_(2)system provides a new platform to study the superconductivity with hole doping on the Fe site of iron-based superconductors.
基金supported by the National Natural Science Foundation of China(Grant Nos.92365302,92065201,12488101,22325203,92265105,12074247,12174252,and 52102336)the Ministry of Science and Technology of China(Grant Nos.2019YFA0308600 and 2020YFA0309000)+1 种基金the Science and Technology Commission of Shanghai Municipality(Grant Nos.2019SHZDZX01,19JC1412701,20QA1405100,24LZ1401000,and LZPY2024-04)the financial support from Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302500)。
文摘Topological superconductor islands are thought to be the building blocks of topological quantum bits.We produced single-crystalline VSi_(x)islands with well-defined side facets and island size more than 200nm using molecular beam epitaxy on Si substrate heated to 950℃throughout the growth process.By means of scanning tunneling spectroscopy,we revealed dynamical Coulomb blockade and superconductivity on isolated islands and on islands being connected by superconducting wetting layer respectively.Bi_(2)Te_(3)films were further deposited on VSi_(x)islands.Robust and homogenous proximity effect induced superconductivity was observed on various facets of the Bi_(2)Te_(3)/VSi_(x)hetero-nanostructure.Furthermore,our high-resolution spectroscopy identified Bosonic mode excitations on the topological superconductor islands.These results may establish a playground for the vortex Majorana islands.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFE0202600)the National Natural Science Foundation of China(Grant No.52272268)+3 种基金the Key Research Program of Frontier SciencesCAS(Grant No.QYZDJ-SSWSLH013)the Informatization Plan of Chinese Academy of Sciences(Grant No.CAS-WX2021SF-0102)the Youth Innovation Promotion Association of CAS(Grant No.2019005)。
文摘The kagome lattice,characterized by a hexagonal arrangement of corner-sharing equilateral triangles,has garnered significant attention as a fascinating quantum material system that hosts exotic magnetic and electronic properties.The identification and characterization of this class of materials are critical for advancing our understanding of their role in emergent phenomena such as superconductivity.In this study,we developed a high-throughput screening framework for the systematic identification and classification of superconducting materials with kagome lattices,integrating them into established materials databases.Leveraging the Materials Project(MP)database and the MDR Super Con dataset,we analyzed over 150000 inorganic compounds and cross-referenced 26000 known superconductors.Using geometry-based structural modeling and experimental validation,we identified 129 kagome superconductors belonging to 17 distinct structural families,many of which had not previously been recognized as kagome systems.The materials are further classified into three categories in terms of topological flat bands,clean band structures,and coexisting magnetic or charge density wave(CDW)orderings.Based on these results,we established a database comprising 129 kagome superconductors,including the detailed crystallographic,electronic,and superconducting properties of these materials.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1611103 and 2022YFA1403203)the Innovation Program for Quantum Science and Technology(Grant Nos.2024ZD0301300 and 2021ZD0302802)the National Natural Science Foundation of China(Grant Nos.12474128,12374133,12204008,and 12104004)。
文摘Iron-based superconductors(FeSCs)feature a complex phase diagram,and their diverse cleavage terminations offer a versatile platform for modulating surface electronic states and investigating the underlying superconducting mechanisms.In this study,we explore the surface modulation of KCa_(2)Fe_(4)As_(4)F_(2)using scanning tunneling microscopy/spectroscopy.Cryogenically cleaved surfaces reveal multiple configurations,including√2×√2 reconstruction,1×2 and 1×3 stripes,as well as nanoscale vacancies.Reducing potassium coverage induces hole doping,which shifts the density of states peak toward the Fermi level and suppresses the superconducting gap from 4.8 meV to 3.2 meV.This behavior is reminiscent of the Van Hove singularity observed in hole-doped 122-type FeSCs.The band structure does not undergo a simple rigid shift,and the evolution of superconductivity can be attributed to the interplay between surface carriers and electronic correlations.Additionally,a V-shaped gap is observed at a unique location preserving the FeAs bilayer structure,where interlayer coupling effects are likely involved.The diversity of surface structures and electronic states in K12442 enhances our understanding of FeSCs and facilitates the modulation and application of FeAs superconducting layers.
基金supported by the National Natural Science Foundation of China(Grant Nos.62476278,12434009,12204533)the National Key R&D Program of China(Grant No.2024YFA1408601)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302402)。
文摘The discovery of high-temperature superconducting materials holds great significance for human industry and daily life.In recent years,research on predicting superconducting transition temperatures using artificial intelligence(AI)has gained popularity,with most of these tools claiming to achieve remarkable accuracy.However,the lack of widely accepted benchmark datasets in this field has severely hindered fair comparisons between different AI algorithms and impeded further advancement of these methods.In this work,we present HTSC-2025,an ambient-pressure high-temperature superconducting benchmark dataset.This comprehensive compilation encompasses theoretically predicted superconducting materials discovered by theoretical physicists from 2023 to 2025 based on BCS superconductivity theory,including the renowned X_(2)YH_(6)system,perovskite MXH_(3)system,M_(3)H_(8)system,cage-like BCN-doped metal atomic systems derived from LaH_(10)structural evolution,and two-dimensional honeycomb-structured systems evolving from MgB_(2).In addition,we note a range of approaches inspired by physical intuition for designing high-temperature superconductors,such as hole doping,the introduction of light elements to form strong covalent bonds,and the tuning of spin-orbit coupling.The dataset presented in this paper is openly available at Science DB.The HTSC-2025 benchmark has been open-sourced on Hugging Face at https://huggingface.co/datasets/xiao-qi/HTSC-2025 and will be continuously updated,while the Electronic Laboratory for Material Science platform is available at https://in.iphy.ac.cn/eln/link.html#/124/V2s4.
基金supported by the National Natural Science Foundation of China(Nos.12374004 and 12174141)the National Key R&D Program of China(No.2023YFA1406200)。
文摘Exploring novel superconductors is a crucial topic in condensed matter physics.There are few reports on the superconductivity of fluorine due to the extremely high pressures required for its metallization.Here,metallization and superconductivity of fluorine were achieved in MgF_(5)at 120 GPa by exploiting the high-pressure s-d transition of doped Mg.The unexpected Mg-F covalent bonding induced by Mg-d and F-p orbital interactions led to fluorine metallization and the formation of an F skeleton similar to a H-cage.The high density of states(DOS)from the F skeleton and phonon softening from strong Fermi surface nesting contribute to a high superconducting transition temperature(Tc).The Tc of Pmmm-MgF_(5)at 120 GPa is 14.02 K,with strong electron-phonon coupling(λ=0.84),which is close to that of Li_(6)P at 270 GPa(λ=1.01).This is the first observation of superconductivity in main-group metal fluorides.Additionally,two near-monatomic F atoms exist in the interstitial region of MgF_(5),significantly enhancing electron-phonon coupling.This work challenges the traditional view of main-group metal fluorides and provides deeper insights into the superconductivity and physicochemical properties of fluorine.
基金supported by the National Natural Science Foundation of China(Grant Nos.12232005 and 12072101).
文摘Large-grain REBa_(2)Cu_(3)O_(7-δ)(REBCO,RE=rare earth)bulk superconductors offer promising magnetic field trapping capabilities due to their high critical current density,making them ideal for many important applications such as trapped field magnets.However,for such large-grain superconductor bulks,there are lots of voids and cracks forming during the process of melting preparation,and some of them can be up to hundreds of microns or even millimeters in size.Consequently,these larger size voids/cracks pose a great threat to the strength of the bulks due to the inherent brittleness of superconductor REBCO materials.In order to ensure the operational safety of related superconducting devices with bulk superconductors,it is firstly important to accurately detect these voids/cracks in them.In this paper,we proposed a method for quantitatively evaluating multiple voids/cracks in bulk superconductors through the magnetic field and displacement response signals at superconductor bulk surface.The proposed method utilizes a damage index constructed from the magnetic field signals and displacement responses to identify the number and preliminary location of multiple defects.By dividing the detection area into subdomains and combining the magnetic field signals with displacement responses within each subdomain,a particle swarm algorithm was employed to evaluate the location and size parameters of the defects.In contrast to other evaluation methods using only magnetic field or displacement response signals,the combined evaluation method using both signals can identify the number of cracks effectively.Numerical studies demonstrate that the morphology of voids and cracks reconstructed using the proposed algorithm ideally matches real defects and is applicable to cases where voids and cracks coexist.This study provides a theoretical basis for the quantitative detection of voids/cracks in bulk superconductors.
基金supported by the National Key Research and Development Program of China(Grant Nos.2024YFA1408400,2023YFA1406100,2023YFA1607400,2022YFA1403800,and 2022YFA1403203)the National Natural Science Foundation of China(Grant Nos.12474055,12404067,12025408,52025026,and U23A6003)+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2024PG0003)the Outstanding Member of Youth Promotion Association of Chinese Academy of Sciences(Grant No.Y2022004)supported by the CAC station of Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF)。
文摘Compared to traditional superhard materials with high electron density and short,strong covalent bonds,alloy materials mainly composed of metallic bonding structures typically have great toughness and lower hardness.Breaking through the limits of alloy materials is a preface and long-term topic,which is of great significance and value for improving the comprehensive mechanical properties of alloy materials.Here,we report on the discovery of a cubic alloy semiconducting material Ti_(2)Co with a large Vickers of hardness K_(v)^(exp)∼6.7GPa and low fracture toughness of K_(IC)^(exp)∼1.51MPa·m^(1/2).Unexpectedly,the K_(v)^(exp)∼6.7GPa is nearly triple of the K_(v)^(cal)∼2.66GPa predicted by density functional theory(DFT)calculations and theK_(IC)^(exp)∼1.51MPa·m^(1/2)is about one or two orders of magnitude smaller than that of ordinary titanium alloy materials(K_(IC)^(exp)∼30-120MPa·m^(1/2)).These specifications place Ti_(2)Co far from the phase space of the known alloy materials.Upon incorporation of oxygen into structural void positions,both values were simultaneously improved for Ti_(4)Co_(2)O to∼9.7GPa and∼2.19MPa·m^(1/2),respectively.Further DFT calculations on the electron localization function of Ti_(4)Co_(2)X(X=B,C,N,O)vs.the interstitial elements indicate that these simultaneous improvements originate from the coexistence of Ti-Co metallic bonds,the emergence of newly oriented Ti-X covalent bonds,and the increase of electron concentration.Moreover,the large difference between K_(v)^(exp)and K_(v)^(cal)of Ti_(2)Co suggests underlying mechanism concerning the absence of the O(16d)or Ti_(2)-O bonds in the O-(Ti_(2))_(6) octahedron.This discovery proposes a new pathway to simultaneously improve the comprehensive mechanical performances and illuminates the path of exploring superconducting materials with excellent mechanical performances.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.62476278,12434009,and 12204533)the National Key R&D Program of China(Grant No.2024YFA1408601)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302402)。
文摘The discovery of new superconducting materials,particularly those exhibiting high critical temperature(Tc),has been a vibrant area of study within the field of condensed matter physics.Conventional approaches primarily rely on physical intuition to search for potential superconductors within the existing databases.However,the known materials only scratch the surface of the extensive array of possibilities within the realm of materials.
基金Project supported by the National Key Research and Development Project of China(Grant Nos.2024YFA1207700 and 2022YFA1204100)the National Natural Science Foundation of China(Grant No.62488201)+2 种基金the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-003)the Youth Innovation Promotion Association(Grant No.2023005)the Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘The interplay between 2a_(0)×2a_(0)charge density wave(CDW),nematicity and superconductivity in AV_(3)Sb_(5)(A=K,Rb,Cs)compounds gives rise to a rich landscape of intriguing physical phenomena.In addition to the 2a_(0)×2a_(0)CDW,a unidirectional 4a_(0)stripe CDW is also observed on the Sb surface of RbV3Sb5and CsV3Sb5.However,reports of stripe-like CDWs in KV3Sb5have been limited.Here,we report the first observation of a long-range unidirectional stripe order with a 6a_(0)modulation period on the Sb surface of KV_(3)Sb_(5),coexisting with the 2a_(0)×2a_(0)CDW.Notably,the intensity of the6a_(0)stripes in STM topographies exhibits pronounced contrast reversal between opposite bias voltages.Additionally,the wave vector of the 6a_(0)modulation shows no energy-dependent dispersion,confirming its CDW origin.Furthermore,the6a_(0)CDW is robust under a 7 T out-of-plane magnetic field and persists over a temperature range from 215 mK to 720 mK.These results provide compelling evidence for the emergence of a long-range unidirectional CDW in KV_(3)Sb_(5).
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403903,2023YFA1406100,2018YFA0305800,and 2022YFA1204100)the National Natural Science Foundation of China(Grant Nos.12304075,11834014,61888102,and 12447101)+2 种基金Chinese Academy of Sciences(Grant Nos.XDB33010200 and 2022YSBR-048)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)the National Science and Technology Major Project(Grant No.2024ZD0300500)。
文摘The kagome lattice,naturally encompassing Dirac fermions,flat bands,and van Hove singularities,tends to intertwine exotic electronic states.Revealing the characteristics of its Fermi surface will help clarify the nature of the complex quantum phenomena in kagome material.Here we report the Fermi surface properties of the novel kagome metal CsTi_(3)Bi_(5)by the de Haas-van Alphen oscillations.The observed oscillations are clear and consist of six principal frequencies ranging from 214 T to 1013 T.The angular dependence of the frequency implies a quasi-two-dimensional electronic structure.In addition,the geometry phase corresponding to 281 T,determined by direct Lifshitz-Kosevich formula fitting,yields a value close toπ,which may indicate a band structure with nontrivial topological property.These results underscore the potential of CsTi_(3)Bi_(5)as a promising platform to explore the interplay between topological order,electronic nematicity,and superconductivity.
基金Project supported partly by the Open Research Program in State Key Laboratory of Millimeter Waves of China(Grant No.K200802)partly by the National Natural Science Foundation of China(Grant No.60971122)
文摘The transmission coefficients of electromagnetic （EM） waves due to a superconductor-dielectric superlattice are numerically calculated. Shift operator finite difference time domain （SO-FDTD） method is used in the analysis. By using the SO-FDTD method, the transmission spectrum is obtained and its characteristics are investigated for different thicknesses of superconductor layers and dielectric layers, from which a stop band starting from zero frequency can be apparently observed. The relation between this low-frequency stop band and relative temperature, and also the London penetration depth at a superconductor temperature of zero degree are discussed, separately. The low-frequency stop band properties of superconductor-dielectric superlattice thus are well disclosed.
基金Project supported by the National Natural Science Foundation of China(Grant No.11974293)。
文摘We investigate the topological properties of twisted bilayer superconductors with different even-parity pairings in each layer.In the presence of spin-orbit coupling,the Hamiltonian is mapped into an effective odd-parity superconductor.Based on this,we deduce the topological properties by examining the relative configuration between Fermi surface and Dirac pairing node.We show that mixed Rashba and Dresselhaus spin-orbit coupling and anisotropic hopping terms,which break the C_(4)symmetry of the Fermi surface,can induce first-order topological superconductors with non-zero bulk Chern number.This provides a versatile way to control the topological phases of bilayer superconductors by adjusting the twisted angle and chemical potential.We demonstrate our results using a typical twisted angle of 53.13°,at which the translation symmetry is restored and the Chern number and edge state are calculated using the Moir′e momentum.
文摘Using a very useful quantity in physics and chemistry,the electronegativity,we have found that for nearly 70 high-Tc oxide superconductors(HTOS),the average electronegativity is in a narrow range 2.5-2.7.The difference of bond character between the HTOS and the conventional superconductors has been discussed.Finally,two categories of superconductors in terms of the group average electronegativity are suggested.
文摘Solving the Bogoliubov-de Gennes equation, the energy levels of bound statesare obtained in the ferromagnetic superconductor. The Josephson currents in a ferromagneticsuperconductor/Insulator/d-wave superconductor junction are calculated as a function of the exchangefield, temperature, and insulating barrier strength. It is found that the Josephson criticalcurrent is always suppressed by the presence of exchange Geld h and depends on crystalline axisorientation of d-wave superconductor.
文摘We review several recent theoretical and experimental results in the study of superconductor hybrids. This includes the recent experimental advances in the study of superconducting beamsplitters as well as more advanced superconductor hybrid systems including ferromagnets or Majorana fermions. In the same manner, theoretical studies have revealed that such superconductor hybrid systems pave the way towards electronic generation and detection of entanglement as well as possible use cases in quantum computing. We will review the aspects in detail and illustrate the possible next steps to be taken.
文摘An international research team consisting of scientists from the Institute of Physics(IOP),Chinese Academy of Sciences in Beijing,the University of Maryland(UMD),and the Lawrence Berkeley National Laboratory(LBNL)has captured experimental evidence which sheds light on the mechanism of high temperature superconductivity in the so-called cuprate(copper oxide)superconductors,which were first discovered in 1986.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11534003,11874175,11874176,12074138,and 11974134)the Science Challenge Project(Grant No.TZ2016001)+3 种基金the Fundamental Research Funds for the Central Universities(Jilin University,JLU)the Program for JLU Science and Technology Innovative Research Team(JLUSTIRT)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Jilin Province Outstanding Young Talents Project(Grant No.20190103040JH).
文摘A dream long held by physicists has been to raise the critical temperature(Tc)—the temperature below which the material exhibits no electrical resistance—of a superconductor to room temperature.The most recent excitement in that regard has centered on rare-earth superhydrides,of which LaH10 at 190 GPa has a remarkably high Tc of 260 K.
基金The authors acknowledge funding support from the Natural Science Foundation of China under Grant Nos.21873017 and 21573037the Postdoctoral Science Foundation of China under Grant No.2013M541283+1 种基金the Natural Science Foundation of Hebei Province(Grant No.B2021203030)the Natural Science Foundation of Jilin Province(Grant No.20190201231JC).
文摘Although it was proposedmany years ago that compressed hydrogen should be a high-temperature superconductor,the goal of room-temperature superconductivity has so far remained out of reach.However,the successful synthesis of the theoretically predicted hydrides H3S and LaH10 with high superconducting transition temperatures TC provides clear guidance for achieving this goal.The existence of these superconducting hydrides also confirms the utility of theoretical predictions in finding high-TC superconductors.To date,numerous hydrideshave been studied theoretically or experimentally,especially binary hydrides.Interestingly,some of them exhibit superconductivity above 200 K.To gain insight into these high-TC hydrides(>200 K)and facilitate further research,we summarize their crystal structures,bonding features,and electronic properties,as well as their superconductingmechanism.Based on hydrogen structuralmotifs,covalentH3Swith isolated hydrogen and several clathrate superhydrides(LaH10,YH9,and CaH6)are highlighted.Other predicted hydrides with various H-cages and two-dimensional H motifs are also discussed.Finally,we present a systematic discussion of the common features,current problems,and future challenges of these high-TC hydrides.
