CHIRALITY TUNNELING IN MESOSCOPIC ANTIFERROMAGNETIC DOMAIN-WALLS

We consider a domain wall in the mesoscopic quasi-one-dimensional samp le (wire or stripe) of weakly anisotropic two-sublattice antiferromagn et, and estimate the probability of tunneling between two domain wall states with different chirality, in the Limits of weak and strong rhom bicity. Topological effects forbid tunneling for the systems with half -integer spin S of magnetic atoms which consist of an odd number of ch ains n(perpendicular to). External magnetic field yields an additional contribution to the Berry phase, resulting in oscillating field depen dence of the tunneling rate with the period proportional to root JK/n( perpendicular to), where J and K are exchange and anisotropy constants , respectively, and in the appearance of two different tunnel splittin gs in any setup involving a mixture of odd and even n(perpendicular to ). [S0163-1829(98)06242-0].