Control of Critical Current of Intrinsic Josephson Junctions Due to Spin Injection

Abstract

We have investigated the influence of the ferromagnet magnetization on the critical current Ic of the intrinsic Josephson junctions (IJJs) in Co/Au/Bi2Sr2CaCu2Oy(BSCCO) mesa structures under applied magnetic fields parallel to the layer. The mesa structure with lateral dimensions of 5×5 μm2 and 2×13 μm2 were fabricated by using electron beam lithography, photolithography and Ar ion milling. Before an application of magnetic field B, the current-voltage characteristics of the mesa showed the typical multiple resistive branches with hysteresis similar to those of conventional IJJs. However, by applying B the Ic was considerably suppressed and the Ic-B curve showed hysteresis in contrast to conventional IJJs. Furthermore, the suppression of Ic was found to be minimized at the coercive filed of the Co layer. This implies that the Ic is significantly affected by the domain structure of the Co formed on IJJs. From these results we found that the Ic of IJJs in the Co/Au/BSCCO mesa can be control by small magnetic field and the hybrid structure of ferromagnet and IJJs might be applicable for a switching device and other spintronics devices.