Artificial magnetic granularity effects on patterned epitaxial YBa2Cu3O7-x thin films

作者：Bartolome E^*; Palau A; Gutierrez J; Granados X; Pomar A; Puig T; Obradors X; Cambel V; Soltys J; Gregusova D; Chen D X; Sanchez A

来源：Physical Review B, 2007, 76(9): 094508.

DOI：10.1103/PhysRevB.76.094508

An artificial "multigranular" YBCO thin film has been prepared by patterning a network of gridlines, emulating the current-restricting behavior of grain boundaries. This model system allowed us to investigate the magnetic effects of granularity and current percolation problem, having control on the geometry, number of grains, and ratio of inter-to-intragrain critical-current density reduction, J(c)(GB)/J(c)(G). The dc magnetization cycle at 5 K showed a peak shift to a positive applied magnetic field value, typically ascribed to granularity. ac measurements performed up to very high driving ac magnetic fields show that ac losses are dominated by dissipation over the whole grain boundary network, whereas the contribution of individual grains cannot be resolved. A high-resolution (< 5 mu m) Hall-probe imaging system has been used to visualize the evolution of the magnetization distribution with a cycled applied magnetic field (at 4.2 and 77 K), and deduce maps of the intragranular and intergranular currents by solving the inverse problem.

• 出版日期2007-9
• 单位中国科学院电工研究所