Thermodynamic theory for thermal-gradient-driven domain-wall motion

X. S. Wang and X. R. Wang
Phys. Rev. B 90, 014414 – Published 14 July 2014

Abstract

Spin waves (or magnons) interact with magnetic domain walls (DWs) in a complicated way that a DW can propagate either along or against magnon flow. However, thermally activated magnons always drive a DW to the hotter region of a nanowire of magnetic insulators under a temperature gradient. We theoretically illustrate why it is surely so by showing that DW entropy is always larger than that of a domain as long as material parameters do not depend on spin textures. Equivalently, the total free energy of the wire can be lowered when the DW moves to the hotter region. The larger DW entropy is related to the increase of magnon density of states at low energy originated from the gapless magnon bound states.

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  • Received 5 June 2014

DOI:https://doi.org/10.1103/PhysRevB.90.014414

©2014 American Physical Society

Authors & Affiliations

X. S. Wang and X. R. Wang*

  • Physics Department, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong and HKUST Shenzhen Research Institute, Shenzhen 518057, China

  • *Corresponding author: phxwan@ust.hk

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Issue

Vol. 90, Iss. 1 — 1 July 2014

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