Two spatially confined La0.8Ca0.2MnO3（LCMO） microbridges with different widths, starting from a single LCMO fihn （3mm×5 mm）, are fabricated by optical lithography. A second new and robust metal-insulator tran...Two spatially confined La0.8Ca0.2MnO3（LCMO） microbridges with different widths, starting from a single LCMO fihn （3mm×5 mm）, are fabricated by optical lithography. A second new and robust metal-insulator transition （MIT） peak at about 75K appears, in addition to the normal MIT at 180 K observed in the standard LCMO film. When the two bridges are processed by currents of high densities, interesting reversible resistance jumps are excited only around the new peak. A stronger dependence of resistance jump on current excitation is found for the bridge with a smaller width. The temperature driven transition between new excited multiple metastable states are involved to explain the interesting low-temperature ultra-sharp jumps.展开更多
We investigate numerically the integer quantum Hall effect in a two-orbital square lattice. The Hall plateau σH=2（e^2/h） is well defined with the Chern number C=±2. With the increasing disorder, both the Hall ...We investigate numerically the integer quantum Hall effect in a two-orbital square lattice. The Hall plateau σH=2（e^2/h） is well defined with the Chern number C=±2. With the increasing disorder, both the Hall plateau and the gap of density of states decrease gradually in width, and finally the gap disappears before vanishing of the Hall plateau. Compared with the Hall plateau induced by the external magnetic field, the one in our system is more robust against disorder. We also find that the transition from the Hall plateau to zero Hall conductance becomes sharper by increasing the size of the system.展开更多
SrTiO3 thin films are epitaxially grown on DyScO3, LaAlO3 substrates with/without buffer layers of DyScO3 and SrRuO3 using laser-MBE. X-ray diffraction methods, such as high resolution X-ray diffraction, grazing incid...SrTiO3 thin films are epitaxially grown on DyScO3, LaAlO3 substrates with/without buffer layers of DyScO3 and SrRuO3 using laser-MBE. X-ray diffraction methods, such as high resolution X-ray diffraction, grazing incident X-ray diffraction, and reciprocal space mapping are used to investigate the lattice structure, dislocation density, in-plane lattice strain distribution along film thickness. From the measurement results, the effects of substrate on film lattice quality and microstructure are discussed.展开更多
Microstructure of NiO-containing Co/Cu/Co spin valves （CCC-SV） annealed at room temperature for nearly four years has been studied by synchrotron radiation X-ray diffraction. With the annealing time expanding, the t...Microstructure of NiO-containing Co/Cu/Co spin valves （CCC-SV） annealed at room temperature for nearly four years has been studied by synchrotron radiation X-ray diffraction. With the annealing time expanding, the thickness of each sub-layer remains nearly unchanged while the interface roughness varies obviously compared with that of samples without annealing. The roughness at the interface of NiO/Co decreases with the annealing time increasing for both of the samples with NiO layer on the top （TSV） and under the bottom （BSV） of CCC-SV. On the other hand, the roughness at Co/Cu interface increases with the annealing time expanding for BSV while it decreases for TSV. These results indicate that the structure of TSV is more stable than that of BSV.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos U1332205,11404169 and 11274153the Natural Science Foundation of Jiangsu Province under Grant No BK20140450the Huaian Science and Technology(Industry)Project under Grant No HAG2014043
文摘Two spatially confined La0.8Ca0.2MnO3（LCMO） microbridges with different widths, starting from a single LCMO fihn （3mm×5 mm）, are fabricated by optical lithography. A second new and robust metal-insulator transition （MIT） peak at about 75K appears, in addition to the normal MIT at 180 K observed in the standard LCMO film. When the two bridges are processed by currents of high densities, interesting reversible resistance jumps are excited only around the new peak. A stronger dependence of resistance jump on current excitation is found for the bridge with a smaller width. The temperature driven transition between new excited multiple metastable states are involved to explain the interesting low-temperature ultra-sharp jumps.
基金Supported by the Natural Science Foundation of Jiangsu Province under Grant No BK20140450the Huaian Science and Technology(Industry)Project under Grant Nos HAG2014043 and HAG2014019the Youth Foundation of Huaiyin Normal University under Grant No 13HSQNZ03
文摘We investigate numerically the integer quantum Hall effect in a two-orbital square lattice. The Hall plateau σH=2（e^2/h） is well defined with the Chern number C=±2. With the increasing disorder, both the Hall plateau and the gap of density of states decrease gradually in width, and finally the gap disappears before vanishing of the Hall plateau. Compared with the Hall plateau induced by the external magnetic field, the one in our system is more robust against disorder. We also find that the transition from the Hall plateau to zero Hall conductance becomes sharper by increasing the size of the system.
基金Supported by National Natural Science Foundation of China (10774065)Science Foundation for Excellent Youth Scholars of Huaiyin Normal University (08QNZCK 005)
文摘SrTiO3 thin films are epitaxially grown on DyScO3, LaAlO3 substrates with/without buffer layers of DyScO3 and SrRuO3 using laser-MBE. X-ray diffraction methods, such as high resolution X-ray diffraction, grazing incident X-ray diffraction, and reciprocal space mapping are used to investigate the lattice structure, dislocation density, in-plane lattice strain distribution along film thickness. From the measurement results, the effects of substrate on film lattice quality and microstructure are discussed.
基金Supported by Open Project of Lab of Solid State Microstructures of Nanjing University (M06007)Doctoral Foundation of Hohai University (2084/40701117)Natural Science Foundation of Hohai University (2084/408307)
文摘Microstructure of NiO-containing Co/Cu/Co spin valves （CCC-SV） annealed at room temperature for nearly four years has been studied by synchrotron radiation X-ray diffraction. With the annealing time expanding, the thickness of each sub-layer remains nearly unchanged while the interface roughness varies obviously compared with that of samples without annealing. The roughness at the interface of NiO/Co decreases with the annealing time increasing for both of the samples with NiO layer on the top （TSV） and under the bottom （BSV） of CCC-SV. On the other hand, the roughness at Co/Cu interface increases with the annealing time expanding for BSV while it decreases for TSV. These results indicate that the structure of TSV is more stable than that of BSV.
