Li Peigang

Fabrication and Characterization of YBa2Cu3Oy Superconducting Nanowires

Ordered YBa2Cu3Oy nanowires have been fabricated by filling YBa2Cu3Oy melting liquid into the pores of the anodized alumina templates. X-ray powder diffraction proves that YBa2Cu3Oy nanowires crystallized in the Y-123 structure. The temperature dependence of ac susceptibility indicates a superconducting transition at 91 K for the YBa2Cu3Oy nanowire array.

Enhancing low-field magnetoresistance of La0.67Ca0.33MnO3 films deposited on anodized aluminium-oxide membranes

In this paper we report a new method to fabricate nanostructured films. La0.67Ca0.33MnO3 (LCMO) nanostructured films have been fabricated by using pulsed electron beam deposition (PED) on anodized aluminium oxide (AAO) membranes. The magnetic and electronic transport properties are investigated by using the Quantum Design physics properties measurement system (PPMS) and magnetic properties measurement system (MPMS). The resistance peak temperature (Tp) is about 85 K and the Curie temperature (Tc) is about 250 K for the LCMO film on an AAO membrane with a pore diameter of 20 nm. Large magnetoresistance ratio (MR) is observed near Tp. The MR is as high as 85% under 1 T magnetic field. The great enhancement of MR at low magnetic fields could be attributed to the lattice distortion and the grain boundary that are induced by the nanopores on the AAO membrane.

Optical and electrical characterization of (BiFeO 3 ) 25 /(La 0.7 Sr 0.3 MnO 3 ) 25 multilayered thin films

(001) oriented(BiFeO 3 ) 25 /(La 0.7 Sr 0.3 MnO 3 ) 25 multilayered thin films are fabricated on (001)SrTiO 3 substrate by rf-magnetron sputtering. UV-vis absorption spectrum analysis in a photon energy range of 1.2-6.4 eV is carried out, and the result shows that in a range of 1.3-2.1 eV the absorption is enhanced compared with that on SrTiO 3 substrate. And the optical band gap of BiFeO 3 is around 2.7 eV, which is in accordance with other reportsed results very well. Furthermore, the current-voltage curves are measured in a temperature range of 100-300 K, and the analyses according to several dielectric conduction models exhibite that the space-charge-limited conduction is dominated in the fabricated (BiFeO 3 ) 25 /(La 0.7 Sr 0.3 MnO 3 ) 25 multilayered thin films.