Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resist...Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resistive switching（RS） behavior in the Au/LCO/Pt devices exhibits a high resistance ratio of ~104 between the high resistance state（HRS） and low resistance state（LRS） and exhibits excellent endurance/retention characteristics.The conduction mechanism of the HRS in the high voltage range is dominated by the Schottky emission, while the Ohmic conduction dictates the LRS and the low voltage range of HRS. The RS behavior in the Au/LCO/Pt devices can be understood by the formation and rupture of conducting filaments consisting of oxygen vacancies,which is validated by the temperature dependence of resistance and x-ray photoelectron spectroscopy results.Further analysis shows that the reset current IR and reset power PR in the reset processes exhibit a scaling law with the resistance in LRS（R0）, which indicates that the Joule heating effect plays an essential role in the RS behavior of the Au/LCO/Pt devices.展开更多
Development of p-type transparent conducting thin films is tireless due to the trade-off issue between optical transparency and conductivity. The rarely concerned low normal state resistance makes Bi-based superconduc...Development of p-type transparent conducting thin films is tireless due to the trade-off issue between optical transparency and conductivity. The rarely concerned low normal state resistance makes Bi-based superconducting cuprates the potential hole-type transparent conductors, which have been realized in Bi_(2)Sr_(2)CaCu_(2)O_(y) thin films. In this study, epitaxial superconducting Bi_(2)Sr_(2)CuO_(y) and Bi_(2)Sr_(1.8)Nd_(0.2)CuO_(y) thin films with superior normal state conductivity are proposed as ptype transparent conductors. It is found that the Bi_(2)Sr_(1.8)Nd_(0.2)CuO_(y) thin film with thickness 15 nm shows an average visible transmittance of 65% and room-temperature sheet resistance of 650 Ω/sq. The results further demonstrate that Bi-based cuprate superconductors can be regarded as potential p-type transparent conductors for future optoelectronic applications.展开更多
The compounds composed of transition metal cations and pnictide anions provide a rich platform for studying novel physical phenomena.Here we report on the observation of a phase transition at~70 K and 145 K in layered...The compounds composed of transition metal cations and pnictide anions provide a rich platform for studying novel physical phenomena.Here we report on the observation of a phase transition at~70 K and 145 K in layered compound EuCu_(4)As_(2)and SrCu_(4)As_(2),respectively.from both the transport and heat capacity.The thermal expansion measurements show that the variation of the lattice parameters(△L_(b)/L_(ab))around T_(P) is much less than that for a typical crystalline phase transition.Our experimental results reveal that the transition in EuCu_(4)As_(2)and SrCu_(4)As_(2)should be driven by subtle structural-distortion.展开更多
The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technologica...The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technological applications.Despite being extensively studied,there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far.Using V_(2)O_(3)thin films grown on r-plane Al2O3 substrates,which exhibit abrupt MIT and structural phase transition,we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements.Our result provides experimental evidence for clarifying this issue,which could form the basis of theoretical studies as well as technological applications in V_(2)O_(3).展开更多
The low-temperature heat capacities are studied for antiperovskite compounds AX M_3（A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co）. A large peak in（C- γ T）/T^3 versus T is observed for each of a total of 18 com...The low-temperature heat capacities are studied for antiperovskite compounds AX M_3（A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co）. A large peak in（C- γ T）/T^3 versus T is observed for each of a total of 18 compounds investigated,indicating an existence of low-energy phonon mode unexpected by Debye T^3 law. Such a peak is insensitive to the external magnetic field up to 80 k Oe（1 Oe = 79.5775 A·m-1）. For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in（C- γ T）/T^3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of X M_6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AX M_3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material（e.g., ZrW_2O_8, Sc F_3）.展开更多
基金Supported by the Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences’Large-Scale Scientific Facility under Grant No U1532149the National Basic Research Program of China under Grant No2014CB931704
文摘Polycrystalline LaCrO3（LCO） thin films are deposited on Pt/Ti/SiO2/Si substrates by pulsed laser deposition and used as the switching material to construct resistive random access memory devices. The unipolar resistive switching（RS） behavior in the Au/LCO/Pt devices exhibits a high resistance ratio of ~104 between the high resistance state（HRS） and low resistance state（LRS） and exhibits excellent endurance/retention characteristics.The conduction mechanism of the HRS in the high voltage range is dominated by the Schottky emission, while the Ohmic conduction dictates the LRS and the low voltage range of HRS. The RS behavior in the Au/LCO/Pt devices can be understood by the formation and rupture of conducting filaments consisting of oxygen vacancies,which is validated by the temperature dependence of resistance and x-ray photoelectron spectroscopy results.Further analysis shows that the reset current IR and reset power PR in the reset processes exhibit a scaling law with the resistance in LRS（R0）, which indicates that the Joule heating effect plays an essential role in the RS behavior of the Au/LCO/Pt devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11604337)。
文摘Development of p-type transparent conducting thin films is tireless due to the trade-off issue between optical transparency and conductivity. The rarely concerned low normal state resistance makes Bi-based superconducting cuprates the potential hole-type transparent conductors, which have been realized in Bi_(2)Sr_(2)CaCu_(2)O_(y) thin films. In this study, epitaxial superconducting Bi_(2)Sr_(2)CuO_(y) and Bi_(2)Sr_(1.8)Nd_(0.2)CuO_(y) thin films with superior normal state conductivity are proposed as ptype transparent conductors. It is found that the Bi_(2)Sr_(1.8)Nd_(0.2)CuO_(y) thin film with thickness 15 nm shows an average visible transmittance of 65% and room-temperature sheet resistance of 650 Ω/sq. The results further demonstrate that Bi-based cuprate superconductors can be regarded as potential p-type transparent conductors for future optoelectronic applications.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFA1600201)the National Natural Science Foundation of China(Grant Nos.U19A2093,U2032214,U2032163,U1732274,11904002,and 11874359)+5 种基金the Collaborative Innovation Program of Hefei Science Center,Chinese Academy of Sciences(CAS)(Grant No.2019HSC-CIP 001)the Youth Innovation Promotion Association of CAS(Grant No.2021117)the Natural Science Foundation of Anhui Province,China(Grant No.1908085QA15)the Director Fund from the Hefei Institutes of Physical Science(HFIPS)(Grant No.YZJJQY202304)the Director Fund from the the Chinese Academy of Sciences and Hefei Institutes of Physical Science(CASHIPS),China(Grant No.E26MMG71131)the High Magnetic Field Laboratory of Anhui Province,China。
文摘The compounds composed of transition metal cations and pnictide anions provide a rich platform for studying novel physical phenomena.Here we report on the observation of a phase transition at~70 K and 145 K in layered compound EuCu_(4)As_(2)and SrCu_(4)As_(2),respectively.from both the transport and heat capacity.The thermal expansion measurements show that the variation of the lattice parameters(△L_(b)/L_(ab))around T_(P) is much less than that for a typical crystalline phase transition.Our experimental results reveal that the transition in EuCu_(4)As_(2)and SrCu_(4)As_(2)should be driven by subtle structural-distortion.
基金Supported by the National Key R&D Program of China(Grant No.2017YFA0403600)Joint Funds of the National Natural Science Foundation of China and the Chinese Academy of Sciences Large-Scale Scientific Facility(Grant No.U1532149).
文摘The relationship between structural and electronic phase transitions in V_(2)O_(3)thin films is of critical importance for understanding of the mechanism behind metal–insulator transition(MIT)and related technological applications.Despite being extensively studied,there are currently no clear consensus and picture of the relation between structural and electronic phase transitions so far.Using V_(2)O_(3)thin films grown on r-plane Al2O3 substrates,which exhibit abrupt MIT and structural phase transition,we show that the electronic phase transition occurs concurrently with the structural phase transition as revealed by the electrical transport and Raman spectra measurements.Our result provides experimental evidence for clarifying this issue,which could form the basis of theoretical studies as well as technological applications in V_(2)O_(3).
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2011CBA00111)the National Natural Science Foundation of China(Grant Nos.51322105,U1632158,51301165,and 51301167)
文摘The low-temperature heat capacities are studied for antiperovskite compounds AX M_3（A = Al, Ga, Cu, Ag, Sn, X = C,N, M = Mn, Fe, Co）. A large peak in（C- γ T）/T^3 versus T is observed for each of a total of 18 compounds investigated,indicating an existence of low-energy phonon mode unexpected by Debye T^3 law. Such a peak is insensitive to the external magnetic field up to 80 k Oe（1 Oe = 79.5775 A·m-1）. For compounds with smaller lattice constant, the peak shifts towards higher temperatures with a reduction of peak height. This abnormal peak in（C- γ T）/T^3 versus T of antiperovskite compound may result from the strongly dispersive acoustic branch due to the heavier A atoms and the optical-like mode from the dynamic rotation of X M_6 octahedron. Such a low-energy phonon mode may not contribute negatively to the normal thermal expansion in AX M_3 compounds, while it is usually concomitant with negative thermal expansion in open-structure material（e.g., ZrW_2O_8, Sc F_3）.
