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TT: Fachverband Tiefe Temperaturen
TT 79: Correlated Electrons - Poster Session
TT 79.54: Poster
Mittwoch, 2. April 2014, 15:00–19:00, P2
Phase-space Berry phases in chiral magnets: Skyrmion charge, Dzyaloshinskii-Moriya interaction and Hall effect — •Robert Bamler1, Frank Freimuth2, Yuriy Mokrousov2, and Achim Rosch1 — 1Universität zu Köln, Cologne, Germany — 2Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
We present a theory for electronic properties of systems with spin-orbit coupling and smooth magnetic textures, such as chiral magnets. We show that Berry phases in mixed position/momentum space play an important role for both equilibrium and non-equilibrium properties.
In magnetic materials without inversion symmetry (chiral magnets) the spin-orbit coupling can lead to smooth whirls (skyrmions) in the magnetization. They give rise to a strong Hall signal due to the Berry phase an electron picks up when it moves in position space. At the same time, spin-orbit interactions in chiral magnets lead to Berry-phase effects in momentum space, such as the anomalous Hall effect.
In our work we show that the combination of spin-orbit coupling and a magnetic texture leads to new effects due to Berry phases picked up on closed loops in mixed position/momentum space. Using a gradient expansion of the Green's function we identify mixed phase-space Berry phases as the cause of Dzyaloshinskii-Moriya interactions and the charge of skyrmions in metals. By applying the gradient expansion to the Kubo formula we recover the known contributions to the Hall conductivity due to Berry phases in position and momentum space and discuss new contributions due to mixed phase-space Berry phases.