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Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films

Moore’s Law has driven the electronics industry for the past half century. However, the doubling of transistors about every two years is beginning to break down, owing to fundamental limits that arise as they approach the atomic length. As a result, the search for new pathways for electronics has be...

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Main Author: STOSIC, Dusan
Other Authors: LUDERMIR, Teresa Bernarda
Format: doctoralThesis
Language: eng
Published: Universidade Federal de Pernambuco 2019
Subjects:
Inteligência artificial
Filmes ferromagnéticos
Online Access: https://repositorio.ufpe.br/handle/123456789/31432
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spelling ir-123456789-314322019-07-12T05:06:01Z Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films STOSIC, Dusan LUDERMIR, Teresa Bernarda http://lattes.cnpq.br/8767847635452835 http://lattes.cnpq.br/6321179168854922 Inteligência artificial Filmes ferromagnéticos Moore’s Law has driven the electronics industry for the past half century. However, the doubling of transistors about every two years is beginning to break down, owing to fundamental limits that arise as they approach the atomic length. As a result, the search for new pathways for electronics has become crucial. Among potential candidates, the discovery of magnetic textures known as skyrmions has attracted considerable interest and attention in spintronic technology, which relies on both the electron charge and its spin. The unusual topological and particle-like behavior launched skyrmions into the spotlight of scientific research. Topological protected stability, nanoscale size, and low driving currents needed to move them make skyrmions promising candidates for future consumer nanoelectronics. Recent advances in the field have provided all of the basic functions needed for carrying and processing information. In this thesis, we look to advance the current understanding of skyrmion physics, and explore their potential to replace conventional electronics technology. First, the fundamental properties and lifetimes of racetrack skyrmions at room temperature are investigated. We discover that skyrmions can easily collapse at the boundary in laterally finite systems, and propose ways to improve their stability for constrained geometries. Then, pinning of single skyrmions on atomic defects of distinct origins are studied. We reveal that the preferred pinning positions depend on the skyrmion size and type of defect being considered, and discuss applications where control of skyrmions by defects is of particular interest. Next, we explore other magnetic configurations that can compete with skyrmions when considering new materials, and describe a previously unseen mechanism for collapse of skyrmions into cycloidal spin backgrounds. Finally, switching and interactions between skyrmions with distinct topologies are reported. We find that skyrmions transition to higher or lower topologies by absorbing a unit spin texture. The interactions between skyrmions of different topological charges can be attractive or repulsive, leading to the formation of arranged clusters. We conclude with a numerical library for simulating magnetic skyrmions in various scenarios. CNPq A Lei de Moore tem impulsionado a indústria eletrônica no último meio século. No entanto, a duplicação de transistores a cada dois anos está começando a quebrar, devido aos limites fundamentais que surgem à medida que se aproximam a largura atômica. Como resultado a busca por novos caminhos para a eletrônica se tornou crucial. Entre os potenciais candidatos, a descoberta de texturas magnéticas conhecidas como skyrmions atraiu muito interesse e atenção na tecnologia spintrônica, que depende ambos da carga e do spin de elétrons. O comportamento topológico e de partículas lançou skyrmions no centro de atenção da pesquisa científica. Skyrmions são candidatos promissores para a futura nano eletrônica do consumidor devido a sua estabilidade topológica, tamanho em nano escala e baixas correntes necessárias para movê-los. Avanços recentes fornecem todas as funções básicas necessárias para transportar e processar informação baseada em skyrmions. Nesta tese, procuramos avançar o conhecimento atual da física de skyrmions e explorar seu potencial para substituir a tecnologia eletrônica convencional. Primeiro investigamos propriedades sua estabilidade em temperatura ambiente. Descobrimos que skyrmions podem escapar pela borda em sistemas finitos e propomos maneiras de melhorar sua estabilidade para geometrias restritas. Depois estudamos como skyrmions ficam presos em defeitos atômicos de origens distintas. Mostramos que as suas posições dependem do tamanho e do tipo de defeito a ser considerado, e também discutimos aplicações em que o controle de skyrmions por defeitos é de interesse. Em seguida, exploramos outras configurações magnéticas que podem competir com os skyrmions quando novos materiais são considerados, e descrevemos um mecanismo inédito para o colapso de skyrmions em fundos de spin ciclóides. Finalmente, relatamos as comutações e interações entre skyrmions de topologias distintas. Descobrimos que skyrmions transacionam para topologias mais altas ou mais baixas pela absorção de uma textura de spin unitária. As interações entre skyrmions de diferentes cargas topológicas podem ser atrativas ou repulsivas, formando agrupamentos arranjados. Concluímos com uma biblioteca numérica para simular skyrmions magnéticos em vários cenários. 2019-07-11T19:17:49Z 2019-07-11T19:17:49Z 2018-05-02 doctoralThesis https://repositorio.ufpe.br/handle/123456789/31432 eng openAccess Attribution-NonCommercial-NoDerivs 3.0 Brazil http://creativecommons.org/licenses/by-nc-nd/3.0/br/ Universidade Federal de Pernambuco UFPE Brasil Programa de Pos Graduacao em Ciencia da Computacao
institution REPOSITORIO UFPE
collection REPOSITORIO UFPE
language eng
topic Inteligência artificial
Filmes ferromagnéticos
spellingShingle Inteligência artificial
Filmes ferromagnéticos
STOSIC, Dusan
Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
description Moore’s Law has driven the electronics industry for the past half century. However, the doubling of transistors about every two years is beginning to break down, owing to fundamental limits that arise as they approach the atomic length. As a result, the search for new pathways for electronics has become crucial. Among potential candidates, the discovery of magnetic textures known as skyrmions has attracted considerable interest and attention in spintronic technology, which relies on both the electron charge and its spin. The unusual topological and particle-like behavior launched skyrmions into the spotlight of scientific research. Topological protected stability, nanoscale size, and low driving currents needed to move them make skyrmions promising candidates for future consumer nanoelectronics. Recent advances in the field have provided all of the basic functions needed for carrying and processing information. In this thesis, we look to advance the current understanding of skyrmion physics, and explore their potential to replace conventional electronics technology. First, the fundamental properties and lifetimes of racetrack skyrmions at room temperature are investigated. We discover that skyrmions can easily collapse at the boundary in laterally finite systems, and propose ways to improve their stability for constrained geometries. Then, pinning of single skyrmions on atomic defects of distinct origins are studied. We reveal that the preferred pinning positions depend on the skyrmion size and type of defect being considered, and discuss applications where control of skyrmions by defects is of particular interest. Next, we explore other magnetic configurations that can compete with skyrmions when considering new materials, and describe a previously unseen mechanism for collapse of skyrmions into cycloidal spin backgrounds. Finally, switching and interactions between skyrmions with distinct topologies are reported. We find that skyrmions transition to higher or lower topologies by absorbing a unit spin texture. The interactions between skyrmions of different topological charges can be attractive or repulsive, leading to the formation of arranged clusters. We conclude with a numerical library for simulating magnetic skyrmions in various scenarios.
author2 LUDERMIR, Teresa Bernarda
format doctoralThesis
author STOSIC, Dusan
author_sort STOSIC, Dusan
title Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
title_short Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
title_full Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
title_fullStr Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
title_full_unstemmed Numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
title_sort numerical simulations of magnetic skyrmions in atomically-thin ferromagnetic films
publisher Universidade Federal de Pernambuco
publishDate 2019
url https://repositorio.ufpe.br/handle/123456789/31432
_version_ 1641987765162737664
score 13.657419

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