Spin Quenching and Transport by Hidden Dzyaloshinskii-Moriya Interactions

TL;DR

This paper reveals how hidden Dzyaloshinskii-Moriya interactions in uniaxial antiferromagnets influence magnon spin dynamics, leading to spin quenching and enabling controlled spin transport through symmetry and field effects.

Contribution

It uncovers the role of hidden Dzyaloshinskii-Moriya interactions in spin quenching and transport in uniaxial antiferromagnets, a phenomenon previously overlooked due to symmetry considerations.

Findings

Hidden Dzyaloshinskii-Moriya interactions quench magnon spin along the Néel vector.

Certain magnon spins survive at high-symmetry points in the Brillouin zone.

Magnetic field broadens spin distributions, enabling bulk spin transport.

Abstract

Explicit interactions, \textit{e.g.}, dipolar and exchange couplings, usually govern magnetization dynamics. Some interactions may be hidden from the global crystal symmetry. We report that in a large class of \textit{uniaxial} antiferromagnets, a \textit{hidden} Dzyaloshinskii-Moriya interaction with retaining global inversion symmetry quenches the spin of magnon along the N\'eel vector ${\bf n}$, thus forbidding its angular-momentum flow. Some magnon spins, termed ``nodal" and ``corner" spins, survive when they distribute \textit{singularly} at the hot spots, i.e., high-symmetric degeneracy points in the Brillouin zone, and are protected by crystal symmetries. The biased magnetic field along ${\bf n}$ broadens such distributions, allowing bulk spin transport with unique signatures in the magnetic field and temperature dependencies. This explains recent experiments and highlights the role of hidden interaction.