Spin–orbit torque switching in a single (Ga,Mn)(As,P) layer with perpendicular magnetic anisotropy

Abstract

We report the observation of current induced spin–orbit torque (SOT) switching of magnetization in a (Ga,Mn)(As,P) film using perpendicular magnetic anisotropy. Complete SOT switching of magnetization was achieved with current densities as low as 7.4 × 105 A/cm2, which is one to two orders of magnitude smaller than that normally used for SOT switching in ferromagnet/heavy metal bilayer systems. The observed magnetization switching chirality during current scans is consistent with SOT arising from spin polarization caused by the Dresselhaus-type spin–orbit-induced (SOI) fields. The magnitudes of effective SOI fields corresponding to the SOT were obtained from shifts of switching angles in angular dependent Hall measurements observed for opposite current polarities. By measuring effective SOI fields for the [11̄0] and the [110] current directions, we were then able to separate the values of the Dresselhaus-type (HeffD) and Rashba (HeffR) SOI fields. At a current density of 6.0 × 105 A/cm2, these values are HeffD=6.73Oe and HeffR=1.31Oe, respectively. The observed ratio of about 5:1 between Dresselhaus-type and Rashba SOI fields is similar to that observed in a GaMnAs film with an in-plane magnetic anisotropy.

Field-Free Spin–Orbit Torque Magnetization Switching in a Perpendicularly Magnetized Semiconductor (Ga,Mn)As Single Layer

“…Besides, the switching efficiency can be solidly and reversibly manipulated via a gate voltage . Nonetheless, to achieve deterministic magnetization switching in a magnetic system with PMA, a small in-plane external magnetic field H ext is generally necessary to break the symmetry, − but this requirement limits the scalability of the SOT-MRAM devices in practical applications. Therefore, achieving field-free SOT magnetization switching in a ferromagnet single layer is strongly required, because it is a promising tool for obtaining both high efficiency and good scalability of MRAM devices.…”

“…However, spin scattering at the interface significantly limits the SOT switching efficiency. To further advance the writing performance, integration density, and efficiency, it has been recently reported that current-induced SOT magnetization switching can be achieved even in a spin–orbit ferromagnet (a ferromagnet with strong spin–orbit interaction) single layer with perpendicular magnetic anisotropy (PMA). − By applying an in-plane charge current, the SOT induced within a ferromagnet can switch the magnetization of the ferromagnet with an extremely low switching current density. Besides, the switching efficiency can be solidly and reversibly manipulated via a gate voltage .…”