Spin Conductivity in Two-Dimensional Non-Collinear Antiferromagnets

TL;DR

This paper introduces a method to derive the spin current operator in non-collinear antiferromagnets, analyzes spin conductivity at zero temperature, and explores its dependence on magnetic fields, revealing the vanishing of the Drude weight.

Contribution

It presents a novel derivation of the spin current operator for non-collinear antiferromagnets and analyzes the spin conductivity's behavior under magnetic fields at T=0.

Findings

Spin conductivity satisfies the f-sum rule.

Spin Drude weight vanishes at T=0 for any magnetic field.

Spin conductivity depends on the external magnetic field.

Abstract

We propose a method to derive the spin current operator for non-collinear Heisenberg antiferromagnets. We show that the spin conductivity calculated by the spectral representation with the spin current satisfies the f-sum rule. We also study the spin conductivity at T=0 within spin wave theory. We show how the spin conductivity depends on the external magnetic field with changing magnon spectrum. We also find that the spin Drude weight vanishes for any external magnetic field at T=0.