Magnetization-dependent critical current of intrinsic Josephson junctions in Co/Au/Bi2Sr2CaCu2Oy mesa structures

We have investigated the critical current Ic of intrinsic Josephson junctions (IJJs) in Co/Au/Bi2Sr2CaCu2Oy mesa structures as a function of magnetic field. The current-voltage characteristics of the mesas before a magnetization of Co layer showed the multiple quasiparticle branches with hysteresis similar to that of conventional IJJs. On the other hand, the magnetic field dependence of Ic clearly showed hysteretic behavior different from that of conventional IJJs. It is found that such dependence corresponds to the magnetization curve of the Co layer and the Ic has a maximum at the coercive field of the Co layer. The observed modulation of Ic of the Co/Au/Bi2Sr2CaCu2Oy mesa is attributed to the injection of the spin-polarized current.