Chirality tunneling in mesoscopic antiferromagnetic domain walls

TL;DR

This paper investigates quantum tunneling of chirality in mesoscopic antiferromagnetic domain walls, revealing topological constraints and magnetic field effects on tunneling probabilities and rates.

Contribution

It introduces a theoretical analysis of chirality tunneling in antiferromagnetic domain walls, highlighting topological restrictions and magnetic field influences on tunneling behavior.

Findings

Tunneling is forbidden for systems with half-integer spin S and odd number of chains N.

External magnetic fields modify the Berry phase, affecting tunneling splittings.

Tunneling rates oscillate with magnetic field, with a period inversely proportional to N.

Abstract

We consider a domain wall in the mesoscopic quasi-one-dimensional sample (wire or stripe) of weakly anisotropic two-sublattice antiferromagnet, and estimate the probability of tunneling between two domain wall states with different chirality. Topological effects forbid tunneling for the systems with half-integer spin S of magnetic atoms which consist of odd number of chains N. External magnetic field yields an additional contribution to the Berry phase, resulting in the appearance of two different tunnel splittings in any experimental setup involving a mixture of odd and even N, and in oscillating field dependence of the tunneling rate with the period proportional to 1/N.