Weak crystallization of fluctuating skyrmion textures in MnSi

ORAL

Abstract

We report an experimental study of the emergence of non-trivial topological winding and long-range order across the paramagnetic to skyrmion lattice (SkX) transition in the transition metal helimagnet MnSi. Combining measurements of the susceptibility with small angle neutron scattering, neutron resonance spin echo spectroscopy and all-electrical microwave spectroscopy, we find evidence of skyrmion textures in the paramagnetic state exceeding length scales of 103 Å with lifetimes above several 10−9 s. Our experimental findings establish that the paramagnetic to SkX transition in MnSi is well-described by the Landau soft-mode mechanism of weak crystallization, originally proposed in the context of the liquid to crystal transition. As a key aspect of this theoretical model, the modulation-vectors of periodic small amplitude components of the magnetization form triangles that add to zero. In excellent agreement with our experimental findings, these triangles of the modulation-vectors entail the presence of the non-trivial topological winding of skyrmions already in the paramagnetic state of MnSi when approaching the SkX transition.

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Publication: Phys. Rev. X 9, 041059 (2019)

Presenters

  • Franz Xaver Haslbeck

    • Walther-Meißner-Institut, Bavarian Academy of Sciences and Humanities

Authors

  • Franz Xaver Haslbeck

    • Walther-Meißner-Institut, Bavarian Academy of Sciences and Humanities

  • Jonas Kindervater

    • Johns Hopkins University
    • Physics Department, Technical University of Munich, Germany

  • Ioannis Stasinopoulos

    • Physics Department, Technical University of Munich, Germany

  • Andreas Bauer

    • Technische Universität München
    • Physics Department, Technical University of Munich, Germany

  • Felix Rucker

    • Physics Department, Technical University of Munich, Germany

  • Alfonso Chacon

    • Technische Universität München
    • Physics Department, Technical University of Munich, Germany

  • Sebastian Mühlbauer

    • Heinz Maier-Leibnitz Zentrum Garching, Technical University of Munich, Germany

  • Christian Franz

    • Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum Garching, Germany

  • Markus Garst

    • Karlsruhe Institute of Technology
    • Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology, Germany

  • Dirk Grundler

    • Institute of Materials and Laboratory of Nanoscale Magnetic Materials and Magnonics, EPFL Lausanne, Switzerland

  • Christian Pfleiderer

    • Tech Univ Muenchen
    • Physics Department, Technical University of Munich, Germany