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Noninteger-spin magnonic excitations in untextured magnets

Akashdeep Kamra, Utkarsh Agrawal, and Wolfgang Belzig
Phys. Rev. B 96, 020411(R) – Published 21 July 2017
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Abstract

Interactions are responsible for intriguing physics, e.g., the emergence of exotic ground states and excitations, in a wide range of systems. Here, we theoretically demonstrate that dipole-dipole interactions lead to bosonic eigenexcitations with average spin ranging from zero to above in magnets with uniformly magnetized ground states. These exotic excitations can be interpreted as quantum coherent conglomerates of spin magnons, the eigenexcitations when the dipolar interactions are disregarded. We further find that the eigenmodes in an easy-axis antiferromagnet are spin-zero quasiparticles instead of the widely believed spin ± magnons. The latter reemerge when the symmetry is broken by a sufficiently large applied magnetic field. The average spin greater than is accompanied by vacuum fluctuations and may be considered to be a weak form of frustration.

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  • Received 13 December 2016

DOI:https://doi.org/10.1103/PhysRevB.96.020411

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Akashdeep Kamra1,*, Utkarsh Agrawal2, and Wolfgang Belzig1,†

  • 1Department of Physics, University of Konstanz, D-78457 Konstanz, Germany
  • 2Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India

  • *akashdeep.kamra@uni-konstanz.de
  • wolfgang.belzig@uni-konstanz.de

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Issue

Vol. 96, Iss. 2 — 1 July 2017

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