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Title: Dynamics and inertia of a skyrmion in chiral magnets and interfaces: A linear response approach based on magnon excitations

We derive the skyrmion dynamics in response to a weak external drive, taking all the magnon modes into account. A skyrmion has rotational symmetry, and the magnon modes can be characterized by an angular momentum. For a weak distortion of a skyrmion, only the magnon modes with an angular momentum | m | = 1 govern the dynamics of skyrmion topological center. We also determine that the skyrmion inertia comes by way of the magnon modes in the continuum spectrum. For a skyrmion driven by a magnetic field gradient or by a spin transfer torque generated by a current, the dynamical response is practically instantaneous. This justifies the rigid skyrmion approximation used in Thiele's collective coordinate approach. For a skyrmion driven by a spin Hall torque, the torque couples to the skyrmion motion through the magnons in the continuum and damping; therefore the skyrmion dynamics shows sizable inertia in this case. The trajectory of a skyrmion is an ellipse for an ac drive of spin Hall torque.
Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division
Publication Date:
Report Number(s):
LA-UR-17-26376
Journal ID: ISSN 2469-9950; PRBMDO; TRN: US1702841
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 1; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Material Science
OSTI Identifier:
1394985
Alternate Identifier(s):
OSTI ID: 1368611

Lin, Shi-Zeng. Dynamics and inertia of a skyrmion in chiral magnets and interfaces: A linear response approach based on magnon excitations. United States: N. p., Web. doi:10.1103/PhysRevB.96.014407.
Lin, Shi-Zeng. Dynamics and inertia of a skyrmion in chiral magnets and interfaces: A linear response approach based on magnon excitations. United States. doi:10.1103/PhysRevB.96.014407.
Lin, Shi-Zeng. 2017. "Dynamics and inertia of a skyrmion in chiral magnets and interfaces: A linear response approach based on magnon excitations". United States. doi:10.1103/PhysRevB.96.014407. https://www.osti.gov/servlets/purl/1394985.
@article{osti_1394985,
title = {Dynamics and inertia of a skyrmion in chiral magnets and interfaces: A linear response approach based on magnon excitations},
author = {Lin, Shi-Zeng},
abstractNote = {We derive the skyrmion dynamics in response to a weak external drive, taking all the magnon modes into account. A skyrmion has rotational symmetry, and the magnon modes can be characterized by an angular momentum. For a weak distortion of a skyrmion, only the magnon modes with an angular momentum | m | = 1 govern the dynamics of skyrmion topological center. We also determine that the skyrmion inertia comes by way of the magnon modes in the continuum spectrum. For a skyrmion driven by a magnetic field gradient or by a spin transfer torque generated by a current, the dynamical response is practically instantaneous. This justifies the rigid skyrmion approximation used in Thiele's collective coordinate approach. For a skyrmion driven by a spin Hall torque, the torque couples to the skyrmion motion through the magnons in the continuum and damping; therefore the skyrmion dynamics shows sizable inertia in this case. The trajectory of a skyrmion is an ellipse for an ac drive of spin Hall torque.},
doi = {10.1103/PhysRevB.96.014407},
journal = {Physical Review B},
number = 1,
volume = 96,
place = {United States},
year = {2017},
month = {7}
}