title: Topological Hall effect in the A phase of MnSi.
abstract: 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 indicate 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.
authors.affiliation: Physik Department E21, Technische Universität München, James-Franck-Strasse, D-85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Neubauer
authors.forename: C
authors.initials: C
authors.lastname: Pfleiderer
authors.forename: B
authors.initials: B
authors.lastname: Binz
authors.forename: A
authors.initials: A
authors.lastname: Rosch
authors.forename: R
authors.initials: R
authors.lastname: Ritz
authors.forename: P G
authors.initials: PG
authors.lastname: Niklowitz
authors.forename: P
authors.initials: P
authors.lastname: Böni