Phenomena of spin-orbit interaction in non-magnet/ferromagnet junction with symmetry engineering

Abstract

Spin-orbit interaction (SOI) is a principle of generating non-local spin current in non-magnetic materials, and it is being actively researched to solve the problems of conventional electronic device such as miniaturization and power consumption reduction. Recently, magnetization switching and oscillator via SOI have been studied in non-magnet (NM)/ferromagnet (FM) junction. However, most of them are limited to NM/FM single junction. Here, we investigated the spin Hall magnetoresistance (SMR) and spin-orbit torque (SOT), the representative phenomena of SOI, in NM/FM with adjusting symmetry in order to expand understanding and applicability of SOI in NM/FM junction. First, we found experimentally and proved theoretically the new type of SMR which depend on the sign of spin Hall angle in the NM/FM/NM. We also confirmed that the SMR is amplified about twice in the FM/NM/FM. Then, we found a proportional relationship between the amount of SMR and the ratio of NM/FM interfaces per NMs. In addition, by using lateral symmetry breaking, we have been able to eliminate the presence of an external magnetic field which is the limit of the conventional spin-orbit torque magnetization switching. Based in these facts, we have confirmed that the SOI can be manipulated by structural design.