Patent ID: 8124568

Claim:
An oxide superconductor comprising: a substrate; and an oxide superconductor film formed on the substrate to have high crystallinity with a <001> direction of crystal grains being oriented substantially perpendicularly to the substrate and with (100) planes of neighboring ones of the crystal grains being oriented to form therebetween an oblique angle ranging from zero to four degrees or ranging from eighty-six to ninety degrees, wherein the oxide superconductor film has a multilayer structure made up of a plurality of high-density magnetic field trap layers stacked in almost parallel to the substrate and a low-density magnetic field trap layer interposed between adjacent ones of the high-density magnetic field trap layers, and wherein an average grain boundary width of the high-density magnetic field trap layers in a cross-section horizontal to the substrate is less than or equal to eighty nanometers and the average grain boundary width is less than an average grain boundary width of the low-density magnetic field trap layer in its cross-section horizontal to the substrate.