Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 59: Complex Materials II
MM 59.3: Vortrag
Donnerstag, 29. März 2012, 17:30–17:45, H 1029
Pinning of Domain Walls in Helical Magnets — •Bahman Roostaei and Thomas Nattermann — Institute for Theoretical Physics, University of Cologne, Cologne , Germany
Helical magnets are realized in frustrated antiferromagnets, e.g. in rare earth metals Er, Tb, Dy, and Ho or as well in alloys like GdxY1−x and CsCuCl3. In centro-symmetric crystals the helical order may be left or right handed. It was shown recently that helical magnets exhibit a new type of domain walls which includes vortex lines. We have developed a theory for these domain walls that can address their static and dynamic properties based on basic microscopic parameters of the system. In particular we have calculated the elastic constants of such vortex walls and tested our theory numerically. One of the most important questions about domain walls in helical magnets is their interaction with disorder present in the system. We have investigated the effect of disorder on the roughness of these walls. Normally, in the presence of disorder there is a finite threshold force density for depinning the wall. we have modeled the near-threshold dynamics of the vorex walls and estimated the threshold force based on vortex properties and other microscopic parameters of the system.