Wednesday, July 31, 2013

1307.8085 (Robert Bamler et al.)

Phase-space Berry phases and the electric charge of skyrmions in chiral

Robert Bamler, Frank Freimuth, Yuriy Mokrousov, Achim Rosch
The semiclassical motion of electrons in phase space, x=(R, k), in the presence of magnetic textures is influenced by Berry phases described by a 6-component vector potential, A=(A^R, A^k). We argue that for the skyrmion phase of chiral magnets like MnSi all components of the vector potential are important and induce effectively a curvature of phase space. This leads to charge accumulation which turns out to be dominated by the Berry phases picked up on phase-space trajectories involving both position- and momentum directions. This mechanism naturally links skyrmions in chiral magnets to skyrmions in quantum Hall systems, which carry a quantized electric charge. We develop ab initio methods to calculate the charge accumulation and obtain for MnSi a Berry-phase correction to the skyrmion charge of about 2.73 electrons per unit cell and skyrmion.
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