Effect of the interface generated spin current on spin-orbit torque

Abstract

Spin-orbit torque is receiving considerable attention as a next scheme for magnetic random access memory. SOT-MRAM is a next-generation non-volatile memory device with high operating speed and low-power consumption. To achieve the low-power consuming SOT-MRAM, enhancing the efficiency of SOT is essential. In this study, we suggest ways to enhance SOT efficiency by interface engineering. The interface effect of SOT is commonly known to be arise at the non-magnet/ferromagnet interface. However, we suggest other interfaces are also able to contribute to SOT. The SOT in Pt/Co bilayers with various substrates are evaluated. The spin current is generated interface at substrate/non-magnet and it shows that efficiency of SOT can be enhanced by modulating the substrates. Moreover, we investigated the interface generated spin currents in ferromagnet/non-magnet/ferromagnet trilayers. The behavior of spin current along the thickness of non-magnet is observed, and verified the current distribution plays an important role in the interface spin current. By material engineering, controlling the conductivity ratio of ferromagnet and non-magnet, modulating the interface spin current is enabled.