Triple-Point Fermions in Ferroelectric GeTe

Juraj Krempaský, Laurent Nicolaï, Martin Gmitra, Houke Chen, Mauro Fanciulli, Eduardo B. Guedes, Marco Caputo, Milan Radović, Valentine V. Volobuev, Ondřej Caha, Gunther Springholz, Jan Minár, and J. Hugo Dil
Phys. Rev. Lett. 126, 206403 – Published 17 May 2021
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Abstract

Ferroelectric α-GeTe is unveiled to exhibit an intriguing multiple nontrivial topology of the electronic band structure due to the existence of triple-point and type-II Weyl fermions, which goes well beyond the giant Rashba spin splitting controlled by external fields as previously reported. Using spin- and angle-resolved photoemission spectroscopy combined with ab initio density functional theory, the unique spin texture around the triple point caused by the crossing of one spin-degenerate and two spin-split bands along the ferroelectric crystal axis is derived. This consistently reveals spin winding numbers that are coupled with time-reversal symmetry and Lorentz invariance, which are found to be equal for both triple-point pairs in the Brillouin zone. The rich manifold of effects opens up promising perspectives for studying nontrivial phenomena and multicomponent fermions in condensed matter systems.

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  • Received 13 November 2020
  • Revised 16 February 2021
  • Accepted 8 April 2021

DOI:https://doi.org/10.1103/PhysRevLett.126.206403

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Juraj Krempaský1,†, Laurent Nicolaï2, Martin Gmitra3,*, Houke Chen4, Mauro Fanciulli5, Eduardo B. Guedes1, Marco Caputo1, Milan Radović1, Valentine V. Volobuev6,7, Ondřej Caha8, Gunther Springholz9, Jan Minár2, and J. Hugo Dil1,10

  • 1Photon Science Division, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
  • 2New Technologies-Research Center, University of West Bohemia, 301 00 Plzeň 3, Czech Republic
  • 3Institute of Physics, P. J. Šafárik University in Košice, Park Angelinum 9, 040 01 Košice, Slovakia
  • 4Department of Physics, Tsinghua University, Beijing 100084, China
  • 5Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
  • 6International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland
  • 7National Technical University “KhPI”, Kyrpychova Street 2, 61002 Kharkiv, Ukraine
  • 8Department of Condensed Matter Physics, Masaryk University, Kotlářská 267/2, 61137 Brno, Czech Republic
  • 9Institut für Halbleiter-und Festkörperphysik, Johannes Kepler Universität, A-4040 Linz, Austria
  • 10Institut de Physique, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

  • *Corresponding author. martin.gmitra@upjs.sk
  • Corresponding author. juraj.krempasky@psi.ch

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Issue

Vol. 126, Iss. 20 — 21 May 2021

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