Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical ...Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical poling states is demonstrated in C040Fe40B20//（001）-cut Pb（Mgl/3Nb2/3）O3-25PbTiO3 （PMN-PT）. The specific magneto- electric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the （001）-cut PMN-PT substrate.展开更多
A new low temperature Pmmm(120 K) phase was found in high temperature superconductor Sr_2 CuO_(3+δ), which was indicated as a pure electronic phase by resonant x-ray diffraction at Cu K-edge. As shown by x-ray absorp...A new low temperature Pmmm(120 K) phase was found in high temperature superconductor Sr_2 CuO_(3+δ), which was indicated as a pure electronic phase by resonant x-ray diffraction at Cu K-edge. As shown by x-ray absorption fine structure(EXAFS) and x-ray absorption near edge structure(XANES) at Cu K-edge, the strong charge density redistribution and local lattice fluctuations around Cu site at the onset of phase transition were due to the occurrence of superconductive coherence, the redistribution and fluctuation finished at Tc. Finally, the electron–lattice interaction was mainly elaborated to understand the superconductivity of Sr_2 CuO_(3+δ).展开更多
Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures....Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.展开更多
Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction...Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction made of a correlated electron oxide thin film VO_(2) and a conductive 0.05 wt% Nb-doped TiO_(2) single crystal,whose metal-insulator transition(MIT)across the nanoscale heterointerface can be efficiently modulated by visible light irradiation.The magnitude of the MIT decreases from ~350 in the dark state to ~7 in the illuminated state,obeying a power law with respect to the light power density.The junction resistance is switched in a reversible and synchronous manner by turning light on and off.The optical tunability of it is also exponentially proportional to the light power density,and a 320-fold on/off ratio is achieved with an irradiance of 65.6 mW cm^(-2) below the MIT temperature.While the VO_(2) thin film is metallic above the MIT temperature,the optical tunability is remarkably weakened,with a one-fold change remaining under light illumination.These results are co-attributed to a net reduction(~15 meV)in the apparent barrier height and the photocarrier-injection-induced metallization of the VO_(2) heterointerface through a photovoltaic effect,which is induced by deep defect level transition upon the visible light irradiance at low temperature.Additionally,the optical tunability is minimal,resulting from the quite weak modulation of the already metallic band structure in the Schottky-type junction above the MIT temperature.This work enables a remotely optical scheme to manipulate the MIT,implying potential uncooled photodetection and photoswitch applications.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11374010 and 11434009the Fundamental Research Funds for the Central Universities
文摘Using in situ electric-field-modulated anisotropic magnetoresistance measurement, a large reversible and non- volatile in-plane rotation of magnetic easy axis of -35° between the positive and negative electrical poling states is demonstrated in C040Fe40B20//（001）-cut Pb（Mgl/3Nb2/3）O3-25PbTiO3 （PMN-PT）. The specific magneto- electric coupling mechanism therein is experimentally verified to be related to the synchronous in-plane strain rotation induced by 109° ferroelastic domain switching in the （001）-cut PMN-PT substrate.
基金Project supported by the National Basic Research Program of China(Grant Nos.2012CB922004/3,2010CB934501,and 2009CB929502)the Funds of Jilin Province,China(Grant No.JJKH20180860KJ)+1 种基金the National Natural Science Foundation of Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.WK2310000043)
文摘A new low temperature Pmmm(120 K) phase was found in high temperature superconductor Sr_2 CuO_(3+δ), which was indicated as a pure electronic phase by resonant x-ray diffraction at Cu K-edge. As shown by x-ray absorption fine structure(EXAFS) and x-ray absorption near edge structure(XANES) at Cu K-edge, the strong charge density redistribution and local lattice fluctuations around Cu site at the onset of phase transition were due to the occurrence of superconductive coherence, the redistribution and fluctuation finished at Tc. Finally, the electron–lattice interaction was mainly elaborated to understand the superconductivity of Sr_2 CuO_(3+δ).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52072102 and 11775224)It was also partially funded through the Open Foundation of the Hefei National Laboratory for Physical Sciences at the Microscale(Grant No.KF2020002).
文摘Because of the wide selectivity of ferromagnetic and ferroelectric(FE)components,electric-field(E-field)control of magnetism via strain mediation can be easily realized through composite multiferroic heterostructures.Here,an MgO-based magnetic tunnel junction(MTJ)is chosen rationally as the ferromagnetic constitution and a high-activity(001)-Pb(Mg_(1/3)Nb_(2/3))_(0.7)Ti_(0.3)O_(3)(PMN-0.3PT)single crystal is selected as the FE component to create a multiferroic MTJ/FE hybrid structure.The shape of tunneling magnetoresistance(TMR)versus in situ E-fields imprints the butterfly loop of the piezo-strain of the FE without magnetic-field bias.The E-field-controlled change in the TMR ratio is up to-0.27%without magnetic-field bias.Moreover,when a typical magnetic field(~±10 Oe)is applied along the minor axis of the MTJ,the butterfly loop is changed significantly by the E-fields relative to that without magnetic-field bias.This suggests that the E-field-controlled junction resistance is spin-dependent and correlated with magnetization switching in the free layer of the MTJ.In addition,based on such a multiferroic heterostructure,a strain-gauge factor up to approximately 40 is achieved,which decreases further with a sign change from positive to negative with increasing magnetic fields.This multiferroic hybrid structure is a promising avenue to control TMR through E-fields in low-power-consumption spintronic and straintronic devices at room temperature.
基金supported by the Fundamental Research Funds for the Central Universities(108-4115100092)the National Key Research and Development Program of China(2016YFA0300102 and 2017YFA0205004)+2 种基金the National Natural Science Foundation of China(11775224,11504358,11804324 and 52072102)the Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology(2018CXFX001)the Natural Science Research Projects for the Colleges and Universities of Anhui Province(KJ2018A0660)。
文摘Optical control of exotic properties in strongly correlated electron materials is very attractive owing to their potential applications in optical and electronic devices.Herein,we demonstrate a vertical heterojunction made of a correlated electron oxide thin film VO_(2) and a conductive 0.05 wt% Nb-doped TiO_(2) single crystal,whose metal-insulator transition(MIT)across the nanoscale heterointerface can be efficiently modulated by visible light irradiation.The magnitude of the MIT decreases from ~350 in the dark state to ~7 in the illuminated state,obeying a power law with respect to the light power density.The junction resistance is switched in a reversible and synchronous manner by turning light on and off.The optical tunability of it is also exponentially proportional to the light power density,and a 320-fold on/off ratio is achieved with an irradiance of 65.6 mW cm^(-2) below the MIT temperature.While the VO_(2) thin film is metallic above the MIT temperature,the optical tunability is remarkably weakened,with a one-fold change remaining under light illumination.These results are co-attributed to a net reduction(~15 meV)in the apparent barrier height and the photocarrier-injection-induced metallization of the VO_(2) heterointerface through a photovoltaic effect,which is induced by deep defect level transition upon the visible light irradiance at low temperature.Additionally,the optical tunability is minimal,resulting from the quite weak modulation of the already metallic band structure in the Schottky-type junction above the MIT temperature.This work enables a remotely optical scheme to manipulate the MIT,implying potential uncooled photodetection and photoswitch applications.
