Magnetoresistance effect of La(0.72)Ca(0.25)MnO(z)/YBa2Cu3O(y) / La(0.72)Ca(0.25)MnO(z) trilayered films

The magnetoresistance (MR) effects of La(0.72)Ca(0.25)MnO(z)(LCMO) magnetic films and LCMO/YBa2Cu3O(y)(YBCO)/LCMO trilayered films were studied. The LCMO films have an MR ratio of -4 percent when applying 1 T at 77 K and this value is independent of the film thickness from 1500 to 4500 A. In contrast to that, the MR ratio for LCMO/YBCO/LCMO films depends on the thickness of the YBCO layer and is more than 1.5 times as large as that for LCMO films when the thickness of the YBCO layer is less than 2500 A. These results imply that the magnetic spin interaction between the two LCMO layers may exist through the normal-conductive state YBCO layer. (Author)