Magnon-induced superconductivity in a topological insulator coupled to ferro- and antiferromagnetic insulators

ORAL

Abstract

We study the effective interactions between Dirac fermions on the surface of a three-dimensional topological insulator due to the proximity coupling to the magnetic fluctuations in a ferromagnetic or antiferromagnetic insulator. Magnetic fluctuations can mediate attractive interactions between Dirac fermions of both Amperean and BCS type. In the ferromagnetic case, we find pairing between fermions with parallel momenta, so-called Amperean pairing, whenever the effective Lagrangian for the magnetic fluctuations does not contain a quadratic term. If a quadratic term is present, the pairing is instead of BCS type above a certain chemical potential. In the antiferromagnetic case, BCS pairing occurs when the ferromagnetic coupling between magnons on the same sublattice exceeds the antiferromagnetic coupling between magnons on different sublattices. Outside this region in parameter space, we again find that Amperean pairing is realized

*H.G.H. and A.S. were supported by the Research Council of Norway through Grant Number 250985, ”Fundamentals of Low-dissipative Topological Matter”, and Center of Excellence Grant Number 262633, Center for Quantum Spintronics. S. R. was supported by DFG through SPP 1666, ”Topological Insulators: Materials - Fundamental Properties - Devices”.

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Presenters

  • Henning Hugdal

    • Norwegian University of Science and Technology

Authors

  • Henning Hugdal

    • Norwegian University of Science and Technology

  • Stefan Rex

    • Karlsruhe Institute of Technology

  • Flavio Nogueira

    • IFW Dresden

  • Asle Sudbo

    • Dept. of Physics, Norwegian University of Science and Technology
    • Norwegian University of Science and Technology