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Main Authors: Bolognesi, Stefano, Gudnason, Sven Bjarke, Menta, Roberto
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2406.03941
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author Bolognesi, Stefano
Gudnason, Sven Bjarke
Menta, Roberto
author_facet Bolognesi, Stefano
Gudnason, Sven Bjarke
Menta, Roberto
contents The magnetic Skyrmion is described by one control parameter and one length scale. We study the two extreme limits of the control parameter - infinitely large and vanishing - and find that the magnetic Skyrmion becomes a "restricted" magnetic Skyrmion and an O(3) sigma model lump, respectively. Depending on the potential under consideration, the restricted limit manifests differently. In the case of the Zeeman term, the restricted magnetic Skyrmion becomes a "supercompacton" that develops a discontinuity, whereas for the Zeeman term to the power 3/2 it becomes a normal compacton. In both the lump and the restricted limit the solution is given in exact explicit form. We observe that the case of the Zeeman term squared, which can also be understood as a special combination of the Zeeman term and the easy-plane potential - realizable in the laboratory, the analytically exact solution for all values of the coupling - including the Bogomol'nyi-Prasad-Sommerfield (BPS) case - is also of the lump type. Finally, we notice that certain materials (e.g. Fe$_{1-x}$Co$_x$Si or Mn$_{1-x}$Fe$_x$Ge) have a rather large control parameter $ε$ of order 100, making the restricted limit a suitable rough approximation.
format Preprint
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institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Magnetic Skyrmions: from lumps to supercompactons
Bolognesi, Stefano
Gudnason, Sven Bjarke
Menta, Roberto
Mesoscale and Nanoscale Physics
High Energy Physics - Theory
The magnetic Skyrmion is described by one control parameter and one length scale. We study the two extreme limits of the control parameter - infinitely large and vanishing - and find that the magnetic Skyrmion becomes a "restricted" magnetic Skyrmion and an O(3) sigma model lump, respectively. Depending on the potential under consideration, the restricted limit manifests differently. In the case of the Zeeman term, the restricted magnetic Skyrmion becomes a "supercompacton" that develops a discontinuity, whereas for the Zeeman term to the power 3/2 it becomes a normal compacton. In both the lump and the restricted limit the solution is given in exact explicit form. We observe that the case of the Zeeman term squared, which can also be understood as a special combination of the Zeeman term and the easy-plane potential - realizable in the laboratory, the analytically exact solution for all values of the coupling - including the Bogomol'nyi-Prasad-Sommerfield (BPS) case - is also of the lump type. Finally, we notice that certain materials (e.g. Fe$_{1-x}$Co$_x$Si or Mn$_{1-x}$Fe$_x$Ge) have a rather large control parameter $ε$ of order 100, making the restricted limit a suitable rough approximation.
title Magnetic Skyrmions: from lumps to supercompactons
topic Mesoscale and Nanoscale Physics
High Energy Physics - Theory
url https://arxiv.org/abs/2406.03941