Fabrication of YBa2Cu3O(y) - La(0.7)Ca(0.3)MnO(z) - YBa2Cu3O(y) coplanar junctions and their anisotropic current-voltage characteristics

Two types of YBa2Cu3O(y) - La(0.7)Ca(0.3)MnO(z) - YBa2Cu3O(y) (YBCO-LCMO-YBCO) coplanar-type junctions with a 0.2 micron gap were fabricated by electron-beam lithography and Ar-ion-beam milling. One is a junction in which a current flows into the a-b plane (ferromagnetic spin arrangement) of the LCMO and then passes through the channel along the c axis (antiferromagnetic arrangement), and the other is a junction in which the current only passes through the a-b plane. In the former junction, the current-voltage characteristics show nonlinearity which suggests a superconductive linkage, while the latter has linear characteristics. This anisotropy of the proximity effect is attributed to anisotropy of the spin structure, because the LCMO film has a small anisotropy of the normal decay length in the a-b plane and along the c axis. (Author (revised))