Guoliang Liu
Peking University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Guoliang Liu.
Physical Review B | 1997
Guoliang Liu; Guangcheng Xiong; Guohong Li; Guijun Lian; Ke Wu; Sangtian Liu; Jie Li; Shousheng Yan
This work measures the resistivity and Hall coefficient R{sub H} for a series of YBa{sub 2}Cu{sub 3}O{sub 7{minus}y}/PrBa{sub 2}Cu{sub 3}O{sub 7{minus}y} (YBCO/PBCO) superlattices. The Hall coefficient R{sub H} systematically varies with different thicknesses of YBCO or PBCO layers. The Hall number decreases with a decreasing thickness of YBCO layers or increasing thickness of PBCO layers. We investigate the temperature dependence of the Hall angle in YBCO/PBCO superlattices as well. The cotangent Hall angle is also observed to follow a universal T{sup 2} dependence in all superlattices, i.e., cot{theta}{sub H}={alpha}T{sup 2}+C where both {alpha} and C change with the layer thickness. From the results presented herein, we believe that the reduction in carrier density, caused by the magnetic scattering effects and hole filling which occur near the interface, leads to the depression of T{sub c} in the YBCO/PBCO superlattice. {copyright} {ital 1997} {ital The American Physical Society}
Czechoslovak Journal of Physics | 1996
Guohong Li; Guoliang Liu; Min Wang; Mingling Chen; Shiguang Wang; Shousheng Yan
Weak localization magnetoresistance (MR) of a thin Ag film was measured in non-uniform magnetic field created by a superconducting Sn film in intermediate state. MR less than that in uniform field was observed, which is in contrary to the reported MR behavior in the case where the non-uniform field was produced by a superconductor in mixed state. However, the approximately linear behavior of the MR field dependence is in common. The result is discussed based on the different field non-uniformity between intermediate and mixed states. In addition, the detailed structure of the MR indicates a step-like change of the normal domains in intermediate state.
Solid State Communications | 1994
Sangtian Liu; Guangcheng Xiong; Guoliang Liu; Guijun Lian; Guohong Li; Shousheng Yan
Abstract We have studied the 1 f noise behavior of an YBa2Cu3O7/PrBa2Cu3O7 superlattice sample in the normal state, and, measured, for comparison, the 1/f noise power of an YBa2Cu3O7 film and PrBa2Cu3O7 film. The noise power of superlattice sample is about 2 order of magnitude lower than that of YBa2Cu3O7 film, close to the reported noise level in YBa2Cu3O7 single crystal. The results are analysed by a simplified parallel noise sources model. The high level of 1 f noise in PrBa2Cu3O7 film prefers an origin of incipient localization for copper-oxide superconductors in the normal state.
Solid State Communications | 1993
Guohong Li; Yun-Xi Sun; Sangtian Liu; Guoliang Liu; Shousheng Yan; Ling Xiao; Xuekui Fu
Abstract Flux pinning energies and their distributions at 77 K in a Powder-Melt-Textured-Grown YBa 2 Cu 3 O 7−δ sample have been determined by 90° rotating sample magnetic measurements. These measurements are done in three different configurations in which the relative orientations between the trapped flux and the depinning fields vary. Four kinds of peaks are found in the distribution curves. Besides the core pinning with energy of 0.2–0.3 eV, the results suggest the existence of magnetic pinning due to the energy decrease of both the core and the surrounding supercurrents of a flux line. Twin boundaries show the strongest pinning. Interactions between flux lines might have make an additional contribution.
Physica C-superconductivity and Its Applications | 1997
Tong Zhang; Guoliang Liu; Houyong Dong; H.T. Ren; Ling Xiao; Yulei Jiao; Shousheng Yan
Abstract Using Bi Hall probe, the time dependence of the local induction B at different locations on the surface of a melting-textured-growth (MTG) YBCO bulk sample was measured at liquid nitrogen temperature. The behavior of the Hall voltage V H ( t ) shows a marked fluctuation and is qualitatively similar for most geometrically equivalent points on the surface. But for the places with different distances from the center on the surface the V H ( t ) behavior can be quite different.
Solid State Communications | 1995
Guoliang Liu; Min Wang; Guijun Lian; Guohong Li; Sangtian Liu; Guangcheng Xiong; Shousheng Yan
Abstract Measurements of the resistivity and thermoelectric power (TEP) for a series of YBa 2 Cu 3 O 7−δ PrBa 2 Cu 3 O 7−δ ( YBCO PrBCO ) superlattice samples with 2-unit-cell-thick YBCO layer and 2, 4, 6 or 8-unit-cell-thick PrBCO layer in one period are reported. For the sample with 2-unit-cell-thick PrBCO layers, the resistivity of the YBCO layers is larger than that of bulk YBCO samples. The contribution of stoichiometric diffusion and interface scattering is estimated. Its TEP is positive with positive temperature coefficient, different from the typical negative one in bulk YBCO samples with positive TEP values. The property of the YBCO layers changes with increasing thickness of the PrBCO layers. For the sample with 8-unit-cell-thick PrBCO layers, the contribution of the PrBCO layers has to be considered.
Physica B-condensed Matter | 1994
Shousheng Yan; Guoliang Liu; Zheng Lin; Chin Lin; Yufen Zhang; Lianhua Jiang; Guohong Li
Abstract Thermoelectric power measurements are reported for samples with different x in the Gd 1.85−x Pr x Ce 0.15 CuO 4 system for temperature ranging from 80K to 300K. For Pr-rich superconducting samples, thermoelectric power S has a small negative value and is almost temperature independent. It supports the existence of mid-gap states with Fermi level close to the minimum of the density of states. For Gd-rich non-superconducting samples, Cu ions have antiferromagnetic ordering and their behavior of S is close to that of p-type impurity semiconductor.
Physical Review B | 1998
Guohong Li; Mingling Chen; Guoliang Liu; Min Wang; Shiguang Wang; Shousheng Yan
Physical Review B | 1995
Sangtian Liu; Guijun Lian; Guoliang Liu; Min Wang; Guohong Li; Guangcheng Xiong; Shousheng Yan
Physical Review B | 1994
Guoliang Liu; Guangcheng Xiong; Guohong Li; Guijun Lian; Ke Wu; Sangtian Liu; Jie Li; Shousheng Yan