Fundamental Requirements for Deterministic Magnetic Switching

Determine the fundamental requirements for deterministic switching in magnetic systems, defined as the ability of controllable external stimuli to unambiguously drive the system from any initial state to a uniquely designated final state.

Background

Deterministic switching of magnetic order parameters underpins information manipulation in spintronic devices. While ferromagnets allow magnetization reversal via magnetic fields or current-induced torques, antiferromagnets and altermagnets pose greater challenges due to their compensated magnetic moments, making electrical control of the Néel vector difficult and demonstrated only in limited material systems.

Historically, the field lacked a unified understanding of what physical and symmetry conditions are required to guarantee deterministic switching to a unique final state. This paper introduces the concept of switching symmetry and argues that breaking all switching symmetries connecting desired and undesired ground states is a necessary condition, supported by analysis of the Landau–Lifshitz–Gilbert dynamics and case studies in ferromagnets, antiferromagnets, and altermagnets.

References

Despite these substantial experimental advances, one central question remains unresolved: What are the fundamental requirements for deterministic switching, a process in which controllable external stimuli can unambiguously drive the system from any initial state to a uniquely designated final state?

— A Unified Theory of Deterministic Magnetic Switching  (2603.29136 - Fu et al., 31 Mar 2026) in Introduction

We record only the binary top-layer occupancy of each patch, whereas the local state is in fact ternary (a reversed domain in the top layer, in the bottom layer, or neither); a full ternary characterization and a direct demonstration that all $2{N}$ configurations are dynamically accessible are left to future work, so we refrain from asserting exhaustive access to the $2{N}$-element manifold here.

— Emergence of moiré magnetic chaos in twisted bilayer CrI3  (2608.13062 - Park et al., 13 Aug 2026) in Section 3, subsection “Statistical characterization,” final paragraph