February 03, 2012

Improved understanding of magnetism and electrons could help enable advanced spintronics

Knowing how to control the combined magnetic properties of interacting electrons will provide the basis to develop an important tool for advancing spintronics: a technology that aims to harness these properties for computation and communication

Arxiv - Dynamics of Skyrmion Crystal in Metallic Thin Films

We study the collective dynamics of the Skyrmion crystal (SkX) in thin films of ferromagnetic metals resulting from the nontrivial Skyrmion topology. It is shown that the current-driven motion of the crystal reduces the topological Hall effect and the Skyrmion trajectories bend away from the direction of the electric current (the Skyrmion Hall effect). We find a new dissipation mechanism in non-collinear spin textures that can lead to a much faster spin relaxation than Gilbert damping, calculate the dispersion of phonons in the SkX, and discuss effects of impurity pinning of Skyrmions

The paper is published in Physical Review Letters B

Wikipedia on Skyrmion

The skyrmion is a hypothetical particle related to baryons. It was described by Tony Skyrme and consists of a quantum superposition of baryons and resonance states. Skyrmions have been reported, but not conclusively proven, to be in Bose-Einstein condensates, superconductors, and thin magnetic films.

Physical Review Letters B - Skyrmions and anomalous Hall effect in a Dzyaloshinskii-Moriya spiral magnet (2009, 6 pages)

Monte Carlo simulation study of a classical spin model with Dzyalosinskii-Moriya interaction and the spin anisotropy under the magnetic field is presented. We found a rich phase diagram containing the multiple spin spiral (or Skyrme crystal) phases of square, rectangular, and hexagonal symmetries in addition to the spiral spin state. The Skyrme crystal states are stabilized by a spin anisotropy or a magnetic field. The Hall conductivity σxy is calculated within the sd model for each of the phases. Applying a magnetic field induces nonzero uniform chirality and the anomalous Hall conductivity simultaneously. The field dependence of σxy is shown to be a sensitive probe of the underlying magnetic structure. Relevance of the present results to several recent experiments on MnSi is discussed

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