Besides equilibrium behavior,exploring the spin–phonon coupling in multiferroic materials under non-equilibrium conditions is crucial for a deep understanding of the mechanisms as well as their high-frequency applica...Besides equilibrium behavior,exploring the spin–phonon coupling in multiferroic materials under non-equilibrium conditions is crucial for a deep understanding of the mechanisms as well as their high-frequency applications.Here,by utilizing time-resolved refectance spectroscopy,we demonstrate ultrafast spin–phonon coupling dynamics in multiferroic 0.58BiFeO_(3)-0.42Bi_(0.5)K_(0.5)TiO_(3)(BF-BKT)single crystals.With ultrafast laser pumping,coherent acoustic phonons with low damping are created in BF-BKT.Temperature-dependent results indicate that both the frequency and amplitude of laser-induced coherent phonons are sensitive to the emergence of antiferromagnetic order.Moreover,the spin state change driven by external magnetic felds can enhance the oscillation amplitude of the coherent acoustic phonons even above the magnetic Néel temperature.These fndings experimentally confrm that spin–phonon coupling in multiferroic materials exists not only in the spin-ordered state but also in the spin-disordered state,and not only in the equilibrium state but also in the non-equilibrium state excited by ultrafast lasers,suggesting their promising applications in high-frequency devices.展开更多
The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd...The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd_(3)Ga_(5)O_(12)substrates from(111)to(001),the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane.Similar results can also be obtained in the films on Gd_(3)Ga_(5)O_(12)substrates,which identifies the universality of such orientation-induced magnetic anisotropy switching.Additionally,the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique.It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films.These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.展开更多
High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(...High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(TPC) effect is found in this semiconductor LRO film at room temperature. The magnitude of TPC increases almost linearly with the laser power intensities and the photon energies in visible light range. Moreover, the difference in the TPC results under two airflow conditions confirms that both intrinsic photoinduced carrier accumulation and extrinsic photoinduced heating effects contribute to the magnitude of TPC effect.展开更多
The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-m...The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-metal transitions(IMTs) are observed via magneto-optical properties of the crystal. The critical magnetic field(H//c) of IMT for CRMO is found to be as large as 35 T at 5 K. The fine structure of optical spectra identified the antiferromagnetic/ferro-orbital-ordering configurations of Ru 4d orbitals at low temperatures. Meanwhile, the configuration of orbital polarization of such double-layer CRMO single crystal is discussed. These results suggest that the orbital degree of freedom plays an important role in the field induced IMT of multi-orbital system.展开更多
Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build verti...Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.展开更多
The spin-orbit assisted Mott insulator α-RuCl_(3) is a prime candidate for material realization of the Kitaev quantum spin liquid.While little attention has been paid to charge degrees of freedom,charge effects,such ...The spin-orbit assisted Mott insulator α-RuCl_(3) is a prime candidate for material realization of the Kitaev quantum spin liquid.While little attention has been paid to charge degrees of freedom,charge effects,such as electric polarization,may arise in this system.Here,we report distortion-induced local electric polarization in α-RuCl_(3) as evidenced by single-crystal X-ray diffraction,second harmonic generation(SHG)and dielectric measurements.The SHG signal appears at room temperature and develops substantially in the Kitaev paramagnetic state when short-range spin correlations come into play.Despite sizable pyroelectric currents in the Kitaev paramagnetic state,the absence of hysteresis in the polarization-electric field(P-E)points to the shortrange nature of electric polarization.This localized electric polarization is likely the result of distortion-induced charge dimerization,achieved through virtual hopping-induced charge redistribution.In addition,the electric polarization is boosted by short-range spin correlations via spin-phonon coupling in the Kitaev paramagnetic state.Our results emphasize the importance of charge degrees of freedom in α-RuCl_(3),which establish a novel platform to investigate charge effects in Kitaev materials.展开更多
基金supported by the National Key R&D Program of China(Grant No.2021YFA1600200)the National Natural Science Foundation of China(Grant Nos.U2032218 and 12111530283)。
文摘Besides equilibrium behavior,exploring the spin–phonon coupling in multiferroic materials under non-equilibrium conditions is crucial for a deep understanding of the mechanisms as well as their high-frequency applications.Here,by utilizing time-resolved refectance spectroscopy,we demonstrate ultrafast spin–phonon coupling dynamics in multiferroic 0.58BiFeO_(3)-0.42Bi_(0.5)K_(0.5)TiO_(3)(BF-BKT)single crystals.With ultrafast laser pumping,coherent acoustic phonons with low damping are created in BF-BKT.Temperature-dependent results indicate that both the frequency and amplitude of laser-induced coherent phonons are sensitive to the emergence of antiferromagnetic order.Moreover,the spin state change driven by external magnetic felds can enhance the oscillation amplitude of the coherent acoustic phonons even above the magnetic Néel temperature.These fndings experimentally confrm that spin–phonon coupling in multiferroic materials exists not only in the spin-ordered state but also in the spin-disordered state,and not only in the equilibrium state but also in the non-equilibrium state excited by ultrafast lasers,suggesting their promising applications in high-frequency devices.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0303603 and 2016YFA0401803)the National Natural Science Foundation of China(Grant Nos.U2032218,11574316,11874120,61805256,and 11904367)+1 种基金the Plan for Major Provincial Science&Technology Project(Grant No.202003a05020018)the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDB-SSW-SLH011)。
文摘The magnetic anisotropy manipulation in the Sm_(3)Fe_(5)O_(12)(SmIG)films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully.By switching the orientation of the Gd_(3)Ga_(5)O_(12)substrates from(111)to(001),the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane.Similar results can also be obtained in the films on Gd_(3)Ga_(5)O_(12)substrates,which identifies the universality of such orientation-induced magnetic anisotropy switching.Additionally,the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto-optical Kerr effect technique.It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films.These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFA0303603 and 2016YFA0401803the National Natural Science Foundation of China under Grant Nos 11574316,U1532155,61805256 and U1832106the Key Research Program of Frontier Sciences of CAS under Grant No QYZDB-SSW-SLH011
文摘High-quality epitaxial LaRhO3(LRO) thin films on SrTiO3(110) single-crystalline substrates are fabricated by pulsed laser deposition and their photoconductivity properties are studied. The transient photoconductivity(TPC) effect is found in this semiconductor LRO film at room temperature. The magnitude of TPC increases almost linearly with the laser power intensities and the photon energies in visible light range. Moreover, the difference in the TPC results under two airflow conditions confirms that both intrinsic photoinduced carrier accumulation and extrinsic photoinduced heating effects contribute to the magnitude of TPC effect.
基金supported by the National Key R&D Program of China (2017YFA0303603 and 2016YFA0401803)the National Natural Science Foundation of China (U1532153, U1532155, 11574316 and 11774352)+5 种基金the Key Research Program of Frontier Sciences, CAS (QYZDB-SSW-SLH011)Innovative Program of Hefei Science Center CAS (2016FXCX002 and 2016HSC-IU006)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology (2016FXZY001)the One Thousand Youth Talents Program of ChinaWork at Nanjing University was supported by the National Natural Science Foundation of China (11304149 and U1332205)was supported by the Fundamental Research Funds for the Central Universities of China
文摘The magneto-optical spectrum, with magnetic fields up to 42 T, of double layered ruthenates Ca_3(Ru_(0.91)Mn_(0.09))_2O_7(CRMO) single crystal is studied. Both the temperature and magnetic field induced insulator-to-metal transitions(IMTs) are observed via magneto-optical properties of the crystal. The critical magnetic field(H//c) of IMT for CRMO is found to be as large as 35 T at 5 K. The fine structure of optical spectra identified the antiferromagnetic/ferro-orbital-ordering configurations of Ru 4d orbitals at low temperatures. Meanwhile, the configuration of orbital polarization of such double-layer CRMO single crystal is discussed. These results suggest that the orbital degree of freedom plays an important role in the field induced IMT of multi-orbital system.
基金the National Key Research and Development Program of China(No.2017YFA0402902)the National Natural Science Foundation of China(No.1210041089)+1 种基金National Synchrotron Radiation Laboratory(No.KY2060000177),NJUPT-SF(No.NY220163)the US NSF(No.DMR-2005108).
文摘Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.
基金supported by the National Natural Science Foundation of China(Grant Nos.12047564,and 51725104)the support by the National Natural Science Foundation of China(Grant No.12227806)+4 种基金the support by the National Natural Science Foundation of China(Grant Nos.11974036,and 11834014)the Fundamental Research Funds for the Central Universities(Grant No.2024CDJXY022)the Chinesisch-Deutsche Mobilit?tsprogamm of Chinesisch-Deutsche Zentrum für Wissenschaftsf?rderung(Grant No.M-0496)the Open Fund of the China Spallation Neutron Source Songshan Lake Science City(Grant No.DG2431351H)funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)(Grant No.277146847-CRC 1238)。
文摘The spin-orbit assisted Mott insulator α-RuCl_(3) is a prime candidate for material realization of the Kitaev quantum spin liquid.While little attention has been paid to charge degrees of freedom,charge effects,such as electric polarization,may arise in this system.Here,we report distortion-induced local electric polarization in α-RuCl_(3) as evidenced by single-crystal X-ray diffraction,second harmonic generation(SHG)and dielectric measurements.The SHG signal appears at room temperature and develops substantially in the Kitaev paramagnetic state when short-range spin correlations come into play.Despite sizable pyroelectric currents in the Kitaev paramagnetic state,the absence of hysteresis in the polarization-electric field(P-E)points to the shortrange nature of electric polarization.This localized electric polarization is likely the result of distortion-induced charge dimerization,achieved through virtual hopping-induced charge redistribution.In addition,the electric polarization is boosted by short-range spin correlations via spin-phonon coupling in the Kitaev paramagnetic state.Our results emphasize the importance of charge degrees of freedom in α-RuCl_(3),which establish a novel platform to investigate charge effects in Kitaev materials.
