2009/02/28 by A. Neubauer, C. Pfleiderer, B. Binz +4 · 1 citation
Physics and Astronomy · #cond-mat.str-el #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevlett.102.186602
published as Phys. Rev. Lett. 102, 186602 (2009)
arxiv created 2009/05/18 · arxiv updated 2015/05/12
Recent small angle neutron scattering suggests, that the spin structure in the A-phase of MnSi is a so-called triple-Q state, i.e., a superposition of three helices under 120 degrees. Model calculations suggest that this structure in fact is a lattice of so-called skyrmions, i.e., a lattice of topologically stable knots in the spin structure. We report a distinct additional contribution to the Hall effect in the temperature and magnetic field range of the proposed skyrmion lattice, where such a contribution is neither seen nor expected for a normal helical state. Our Hall effect measurements constitute a direct observation of a topologically quantized Berry phase that identifies the spin structure seen in neutron scattering as the proposed skyrmion lattice.