Lead chalcogenides represent a significant class of materials that exhibit intriguing physical phenomena,including remarkable thermoelectric properties and superconductivity.In this study,we present a comprehensive in...Lead chalcogenides represent a significant class of materials that exhibit intriguing physical phenomena,including remarkable thermoelectric properties and superconductivity.In this study,we present a comprehensive investigation on the superconductivity of PbSe single crystal under high pressure.The signature of superconducting(SC)transition starts to appear at 7.2 K under 16.5 GPa.Upon further compression,the SC temperature(T_(c))decreases,and it is reduced to 3.5 K at 45.0 GPa.The negative pressure dependent behavior of T_(c)is consistent with the trend of T_(c)-P relations observed in other lead chalcogenides.The highest T_(c)is 8.0 K observed at 20.5 GPa during decompression process,which is also the highest record among all other PbSe derivatives,such as doped samples,superlattices,and so on.The phase boundaries of the structural and electronic transitions are well defined by Raman spectroscopy,and then phase diagrams are plotted for both compression and decompression processes.This work corrects the previous claim of positive pressure dependence of T_(c)in PbSe and provides clear phase diagrams for intrinsic superconductivity in PbSe under pressure.展开更多
Oxygen vacancy is one of the pivotal factors for tuning/creating various oxide properties.Understanding the behavior of oxygen vacancies is of paramount importance.In this study,we identify a metastable oxygen vacancy...Oxygen vacancy is one of the pivotal factors for tuning/creating various oxide properties.Understanding the behavior of oxygen vacancies is of paramount importance.In this study,we identify a metastable oxygen vacancy ordering state other than the well-known Magnéli phases in TiO2 crystals from both experimental and theoretical studies.The oxygen vacancy ordering is found to be a zigzag chain along the[001]direction in the(110)plane occurring in a wide temperature range of 200–500℃.This metastable ordering state leads to a first-order phase transition accompanied by significant enhancement of dielectric permittivity and a memristive effect featuring a low driving electric field.Our results can improve oxide properties by engineering oxygen vacancies.展开更多
The physical properties of most 2D materials are highly dependent on the nature of their interlayer interaction.In-depth studies of the interlayer interaction are beneficial to the understanding of the physical proper...The physical properties of most 2D materials are highly dependent on the nature of their interlayer interaction.In-depth studies of the interlayer interaction are beneficial to the understanding of the physical properties of 2D materials and permit the development of related devices.Layered magnetic NiPS_(3)has unique magnetic and electronic properties.The electronic band structure and corresponding magnetic state of NiPS_(3)are expected to be sensitive to the interlayer interaction,which can be tuned by external pressure.Here,we report an insulator-metal transition accompanied by the collapse of magnetic order during the 2D-3D structural crossover induced by hydrostatic pressure.A two-stage phase transition from a monoclinic(C2/m)to a trigonal(P31m)lattice is identified via ab initio simulations and confirmed via high-pressure X-ray diffraction and Raman scattering;this transition corresponds to a layer-by-layer slip mechanism along the a-axis.Temperature-dependent resistance measurements and room temperature infrared spectroscopy under different pressures demonstrate that the insulator-metal transition and the collapse of the magnetic order occur at~20 GPa,which is confirmed by low-temperature Raman scattering measurements and theoretical calculations.These results establish a strong correlation between the structural change,electric transport,and magnetic phase transition and expand our understanding of layered magnetic materials.Moreover,the structural transition caused by the interlayer displacement has significance for designing similar devices at ambient pressure.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12374050,12004014,U1930401,and 12375304)the National Key R&D Program of China(Grant Nos.2021YFA1400300 and 2023YFA1608900)the Major Program of the National Natural Science Foundation of China(Grant No.22090041).
文摘Lead chalcogenides represent a significant class of materials that exhibit intriguing physical phenomena,including remarkable thermoelectric properties and superconductivity.In this study,we present a comprehensive investigation on the superconductivity of PbSe single crystal under high pressure.The signature of superconducting(SC)transition starts to appear at 7.2 K under 16.5 GPa.Upon further compression,the SC temperature(T_(c))decreases,and it is reduced to 3.5 K at 45.0 GPa.The negative pressure dependent behavior of T_(c)is consistent with the trend of T_(c)-P relations observed in other lead chalcogenides.The highest T_(c)is 8.0 K observed at 20.5 GPa during decompression process,which is also the highest record among all other PbSe derivatives,such as doped samples,superlattices,and so on.The phase boundaries of the structural and electronic transitions are well defined by Raman spectroscopy,and then phase diagrams are plotted for both compression and decompression processes.This work corrects the previous claim of positive pressure dependence of T_(c)in PbSe and provides clear phase diagrams for intrinsic superconductivity in PbSe under pressure.
基金supported by the National Natural Science Foundation of China(51872001,51572001,11404002,11404003,11474059,and 11674064)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(KF201803)+1 种基金the National Key Research and Development Program of China(2016YFA0300700)Australia Research Council,and the U.S.Department of Energy under Contract no.DE-AC02-05CH11231。
文摘Oxygen vacancy is one of the pivotal factors for tuning/creating various oxide properties.Understanding the behavior of oxygen vacancies is of paramount importance.In this study,we identify a metastable oxygen vacancy ordering state other than the well-known Magnéli phases in TiO2 crystals from both experimental and theoretical studies.The oxygen vacancy ordering is found to be a zigzag chain along the[001]direction in the(110)plane occurring in a wide temperature range of 200–500℃.This metastable ordering state leads to a first-order phase transition accompanied by significant enhancement of dielectric permittivity and a memristive effect featuring a low driving electric field.Our results can improve oxide properties by engineering oxygen vacancies.
基金the National Key Research and Development Program of China(Grant Nos.2016YFA0401503,2018YFA0305700,2017YFA0302904,2020YFA0711502,and 2016YFA0300500)the National Natural Science Foundation of China(Grant Nos.11575288,11974387,U1932215,U1930401,12004014,22090041,and 11774419)+3 种基金the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant Nos.XDB33000000,XDB25000000,and QYZDBSSW-SLH013)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y202003)the CAS Interdisciplinary Innovation Team(Grant No.JCTD-2019-01)ADXRD measurements were performed at 4W2 High Pressure Station,Beijing Synchrotron Radiation Facility(BSRF),which is supported by the Chinese Academy of Sciences(Grant Nos.KJCX2-SW-N20,and KJCX2-SW-N03)。
文摘The physical properties of most 2D materials are highly dependent on the nature of their interlayer interaction.In-depth studies of the interlayer interaction are beneficial to the understanding of the physical properties of 2D materials and permit the development of related devices.Layered magnetic NiPS_(3)has unique magnetic and electronic properties.The electronic band structure and corresponding magnetic state of NiPS_(3)are expected to be sensitive to the interlayer interaction,which can be tuned by external pressure.Here,we report an insulator-metal transition accompanied by the collapse of magnetic order during the 2D-3D structural crossover induced by hydrostatic pressure.A two-stage phase transition from a monoclinic(C2/m)to a trigonal(P31m)lattice is identified via ab initio simulations and confirmed via high-pressure X-ray diffraction and Raman scattering;this transition corresponds to a layer-by-layer slip mechanism along the a-axis.Temperature-dependent resistance measurements and room temperature infrared spectroscopy under different pressures demonstrate that the insulator-metal transition and the collapse of the magnetic order occur at~20 GPa,which is confirmed by low-temperature Raman scattering measurements and theoretical calculations.These results establish a strong correlation between the structural change,electric transport,and magnetic phase transition and expand our understanding of layered magnetic materials.Moreover,the structural transition caused by the interlayer displacement has significance for designing similar devices at ambient pressure.
