Exchange-Enhanced Ultrastrong Magnon-Magnon Coupling in a Compensated Ferrimagnet

Lukas Liensberger, Akashdeep Kamra, Hannes Maier-Flaig, Stephan Geprägs, Andreas Erb, Sebastian T. B. Goennenwein, Rudolf Gross, Wolfgang Belzig, Hans Huebl, and Mathias Weiler
Phys. Rev. Lett. 123, 117204 – Published 13 September 2019
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Abstract

We experimentally study the spin dynamics in a gadolinium iron garnet single crystal using broadband ferromagnetic resonance. Close to the ferrimagnetic compensation temperature, we observe ultrastrong coupling of clockwise and counterclockwise magnon modes. The magnon-magnon coupling strength reaches almost 40% of the mode frequency and can be tuned by varying the direction of the external magnetic field. We theoretically explain the observed mode coupling as arising from the broken rotational symmetry due to a weak magnetocrystalline anisotropy. The effect of this anisotropy is exchange enhanced around the ferrimagnetic compensation point.

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  • Received 25 March 2019
  • Revised 15 July 2019

DOI:https://doi.org/10.1103/PhysRevLett.123.117204

© 2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Lukas Liensberger1,2,*, Akashdeep Kamra3,†, Hannes Maier-Flaig1,2, Stephan Geprägs1, Andreas Erb1, Sebastian T. B. Goennenwein4, Rudolf Gross1,2,5,6, Wolfgang Belzig7, Hans Huebl1,2,5,6, and Mathias Weiler1,2,‡

  • 1Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
  • 2Physik-Department, Technische Universität München, 85748 Garching, Germany
  • 3Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
  • 4Institut für Festkörper- und Materialphysik, Technische Universität Dresden, 01062 Dresden, Germany
  • 5Nanosystems Initiative Munich, 80799 Munich, Germany
  • 6Munich Center for Quantum Science and Technology (MCQST), 80799 Munich, Germany
  • 7Department of Physics, University of Konstanz, 78457 Konstanz, Germany

  • *Lukas.Liensberger@wmi.badw.de
  • Akashdeep.Kamra@ntnu.no
  • Mathias.Weiler@wmi.badw.de

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Issue

Vol. 123, Iss. 11 — 13 September 2019

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