Non-volatile Multistate Magnetic Switching via Spin-orbit Torque and Intrinsic Anisotropy

TL;DR

This paper demonstrates a novel multistate spin-orbit torque device using a SrIrO3/SrRuO3 bilayer, achieving four stable magnetic states and full control over transitions, advancing high-density spintronics.

Contribution

It introduces a new multistate SOT device with four stable states and detailed switching protocols, including real-space magnetic state observation and spin dynamics analysis.

Findings

Four stable magnetic states including in-plane and out-of-plane canted states.

Complete mapping of twelve deterministic transitions between states.

Direct real-space evidence of previously unobserved magnetic states.

Abstract

While current-induced bistate spin-orbit torque (SOT) switching has been well established, deterministic electrical control of multiple magnetic states remains a central challenge in spintronics. Here, we realize a conceptually new multistate SOT device in a SrIrO_3/SrRuO_3 bilayer, hosting four intrinsically stable yet electrically distinguishable magnetic states, including two in-plane canted (IP_c^$\pm$) and two out-of-plane canted (OP_c^$\pm$) states. Pulsed current excitations fully map all twelve deterministic transitions among the four states, establishing a robust switching protocol defined by two characteristic current densities. In-situ scanning nitrogen-vacancy (NV) center magnetometry provides direct real-space evidence for the previously unobserved IP_c^$\pm$ states, and spin dynamics simulations uncover a two-step switching pathway, driven by the concerted action of spin torques and the effective anisotropy field within the fourfold anisotropy landscape. Our demonstration of the intrinsic multistate SOT device directly addresses the density bottleneck of conventional bistate SOT technology, establishing a powerful paradigm for compact, high-speed, and energy-efficient multistate spintronics.