Fractional Topological Charges in 2D Magnets

Fuente: arXiv
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Main Authors: del Ser, Nina, Achchi, Imane El, Rosch, Achim
Format: Preprint
Published: 2023
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_version_ 1866913513243410432
author del Ser, Nina
Achchi, Imane El
Rosch, Achim
author_facet del Ser, Nina
Achchi, Imane El
Rosch, Achim
contents Magnetic skyrmions and antiskyrmions are characterised by an integer topological charge $\mathcal Q =\mp 1$, describing the winding of the magnetic orientation. Half-integer winding numbers, $\mathcal Q=\pm \frac{1}{2}$, can be obtained for magnetic vortices (merons). Here, we discuss the physics of magnets with fractional topological charge which is neither integer nor half-integer. We argue that in ferromagnetic films with cubic anisotropy, textures with $\mathcal Q=\pm\frac{1}{6} $ or $\pm\frac{1}{8}$ arise naturally when three or more magnetic domains meet. We also show that a single magnetic skyrmion with $\mathcal Q =-1$ can explode into four fractional defects, each carrying charge $\mathcal Q=-\frac{1}{4}$. Additionally, we investigate a point defect with a non-quantised fractional charge ($\mathcal Q\neq \frac{n}{m}, n,m\in\mathbb{Z}$) which can move parallel to a magnetic domain wall. Only defects with fractional charge lead to an Aharonov-Bohm effect for magnons. We investigate the resulting forces on a fractional defect due to magnon currents.
format Preprint
id arxiv_https___arxiv_org_abs_2312_11435
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Fractional Topological Charges in 2D Magnets
del Ser, Nina
Achchi, Imane El
Rosch, Achim
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
Magnetic skyrmions and antiskyrmions are characterised by an integer topological charge $\mathcal Q =\mp 1$, describing the winding of the magnetic orientation. Half-integer winding numbers, $\mathcal Q=\pm \frac{1}{2}$, can be obtained for magnetic vortices (merons). Here, we discuss the physics of magnets with fractional topological charge which is neither integer nor half-integer. We argue that in ferromagnetic films with cubic anisotropy, textures with $\mathcal Q=\pm\frac{1}{6} $ or $\pm\frac{1}{8}$ arise naturally when three or more magnetic domains meet. We also show that a single magnetic skyrmion with $\mathcal Q =-1$ can explode into four fractional defects, each carrying charge $\mathcal Q=-\frac{1}{4}$. Additionally, we investigate a point defect with a non-quantised fractional charge ($\mathcal Q\neq \frac{n}{m}, n,m\in\mathbb{Z}$) which can move parallel to a magnetic domain wall. Only defects with fractional charge lead to an Aharonov-Bohm effect for magnons. We investigate the resulting forces on a fractional defect due to magnon currents.
title Fractional Topological Charges in 2D Magnets
topic Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2312.11435