Micromagnetic study of field-free spin-orbit torque switching in ring structure in perpendicular Magnetic Anisotropy System

Abstract

Perpendicular magnetic anisotropy (PMA) system with interfacial Dzyaloshinskii-Moriya interaction (iDMI) have been identified as promising system for deterministic spin-orbit torque (SOT) - induced switching with additional lateral symmetry breaking [1][2]. To increase the switching efficiency, there have been various attempts to achieve switching using structural modifications [3][4][5]. In this study, we investigate the effect of geometrical lateral symmetry breaking on field-free SOT-induced magnetization switching in PMA system using micromagnetic simulations with the MuMax3 program [6]. Our geometrical design consists of a bar structure with dimensions of 800×100×1 nm3 and a ring structure with an inner radius of 100 nm and an outer radius of 200 nm (Fig 1). We report that the location of the ring structure has a significant impact on field-free magnetization switching. Our simulations reveal that magnetization switching occurs when the ring structure is positioned at specific locations along the bar structure. These findings suggest that geometrical factors can be leveraged to control and optimize SOT-induced switching in PMA systems with iDMI. Our study highlights the potential of these systems for future magnetic memory devices with enhanced performance and energy efficiency.