Chirality tunneling in mesoscopic antiferromagnetic domain walls

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, in the limits of weak and strong rhombicity. Topological effects forbid tunneling for the systems with half-integer spin S of magnetic atoms which consist of an odd number of chains ${n}_{\ensuremath{\perp}}.$ External magnetic field yields an additional contribution to the Berry phase, resulting in oscillating field dependence of the tunneling rate with the period proportional to $\sqrt{\mathrm{JK}}{/n}_{\ensuremath{\perp}},$ where J and K are exchange and anisotropy constants, respectively, and in the appearance of two different tunnel splittings in any setup involving a mixture of odd and even ${n}_{\ensuremath{\perp}}.$