SrTiO$_3$/(MgO/)Al$_2O_3$(1120) 위에 쌍에피택셜하게 성장한 Y$_1Ba_2Cu_3O_{7-x}$와 La$_{0.2}Sr_{0.8}MnO_3$ 박막의 조셉슨 및 자기저항 특성연구

Josephson Property and Magnetoresistance in Y$_1Ba_2Cu_3O_{7-x}$ and La$_{0.2}Sr_{0.8}MnO_3$ Films on Biepitaxial SrTiO$_3$/(MgO/)Al$_2O_3$(1120)

Biepitaxial Y$_1Ba_2Cu_3O_{7-x}$ (YBCO) and La$_{0.2}Sr_{0.8}MnO_3$ (LSMO) thin films have been prepared on SrTiO$_3$ buffer layer and MgO seed layer grown on Al$_2O_3$(11${\bar{2}}$0)substrates by dc-sputtering with hollow cylindrical targets, respectively. We charaterized Josephson properties and significantly large magnetoresistance in YBCO and LSMO films with 45$^{\circ}$ grain boundary junction, respectively. The observed working voltage (I$_cR_n$) at 77 K in grain boundary junction was below 10${\mu}$V, which is typical I$_cR_n$ value of single biepitaxial Josephson junction. The field magnetoresistance ratio (MR) of LSMO grain boundary juncoon at 77K was enhanced to 13%, which it was significant MR value with high magnetic field sensitivity at a low field of 250 Oe. These results indicate that inserting the insulating layer instead of the grain boundary layer with metallic phase can be possible to apply a new SIS Josephson junction and a novel magnetic device using spin-polarized tunneling junction.