Chiral dual spin currents field-free perpendicular switching by altermagnet RuO2

TL;DR

This paper demonstrates field-free perpendicular magnetization switching using chiral dual spin currents in an altermagnet RuO2/ferromagnet/heavy metal trilayer, revealing a new mechanism driven by chirality rather than charge current polarity.

Contribution

It introduces a novel physical mechanism for magnetization switching based on chiral dual spin currents in altermagnets, distinct from traditional spin-orbit torque methods.

Findings

Chirality of dual spin currents determines switching polarity.

Intralayer exchange coupling creates an effective in-plane magnetic field.

Switching achieved without external magnetic fields, with low power consumption.

Abstract

Conventional spintronic mechanisms, such as spin-transfer and spin-orbit torques based on the spin current, rely on breaking time-reversal symmetry to manipulate magnetic moments. In contrast, for spatially separated dual spin currents, the time-reversal-invariant vector chirality emerges as a critical factor governing magnetization dynamics. Here, we investigate field-free perpendicular magnetization switching in an altermagnet RuO2/ferromagnet/heavy metal Pt trilayer, driven by chiral dual spin currents (CDSC). We demonstrate that the chirality of these dual spin currents acts as the deterministic role in breaking out-of-plane symmetry. Leveraging the intrinsic spin-splitting effect of the d-wave altermagnet to generate an x-polarized spin component, the interplay of non-collinear spin currents from two adjacent layers induces a helical magnetic texture within the intermediate layer. The resulting intralayer exchange coupling manifests as an effective in-plane magnetic field, facilitating deterministic switching. This distinct physical picture, validated by switching measurements and micromagnetic simulations, reveals that the switching polarity is dictated by chirality rather than charge current polarity. Characterized by the novel symmetry and low power consumption, CDSC offers a promising paradigm for next-generation high-performance spintronic architectures.