Fluctuation-induced Neel and Bloch skyrmions at topological insulator surfaces

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Nogueira F. S., Eremin I., Katmis F., Moodera J. S., van den Brink J., Kravchuk V. P.

PHYSICAL REVIEW B, vol.98, no.6, 2018 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 98 Issue: 6
  • Publication Date: 2018
  • Doi Number: 10.1103/physrevb.98.060401
  • Journal Name: PHYSICAL REVIEW B
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Middle East Technical University Affiliated: No

Abstract

Ferromagnets in contact with a topological insulator have become appealing candidates for spintronics due to the presence of Dirac surface states with spin-momentum locking. Because of this, bilayer Bi2Se3-EuS structures, for instance, show a finite magnetization at the interface at temperatures well exceeding the Curie temperature of bulk EuS. Here, we determine theoretically the effective magnetic interactions at a topological insulator-ferromagnet interface above themagnetic ordering temperature. We show that by integrating out the Dirac fermion fluctuations an effective Dzyaloshinskii-Moriya interaction and magnetic charging interaction emerge. As a result, individual magnetic skyrmions and extended skyrmion lattices can form at the interfaces of ferromagnets and topological insulators, the first indications of which have been very recently observed experimentally.