Odd-Parity Altermagnetism Originated from Orbital Orders

TL;DR

This paper introduces a symmetry-based method to realize odd-parity altermagnetism in layered systems, highlighting orbital order origins and potential for topological phases like quantum spin Hall insulators.

Contribution

It proposes a novel approach to achieve odd-parity altermagnetism via stacking noncentrosymmetric layers and applying layer-flip symmetry, emphasizing orbital order effects over spin-orbit coupling.

Findings

Orbital orders can induce odd-parity spin-splitting without spin-orbit coupling.

The framework enables realization of p- and f-wave altermagnets.

Models host quantum spin Hall phases with protected edge states.

Abstract

Odd-parity spin-splitting plays a central role in spintronics and unconventional superconductivity, yet its microscopic realization in collinear magnetic systems remains elusive. We propose a general symmetry-based strategy for realizing odd-parity altermagnetism by stacking two noncentrosymmetric monolayers in an interlayer antiferromagnetic configuration and applying an in-plane layer-flip operation. In this setting, odd-parity spin-splitting originates from nonrelativistic orbital orders rather than spin-orbit coupling, and is protected by an effective time-reversal symmetry despite the explicit time-reversal symmetry being broken. By exploiting lattice symmetries, our framework enables the realization of both $p$- and $f$-wave altermagnets. The resulting models generically host quantum spin Hall insulator phases, featuring topologically protected helical edge states and quantized spin Hall conductance. Our work expands the landscape of altermagnetic phases and opens a pathway toward spintronics and unconventional superconductivity in altermagnetic systems.