Thermal Stability of Metastable Magnetic Skyrmions

ISBN-13: 9783030660253 / Angielski / Twarda / 2021 / 152 str.

Louise Desplat

Spis treści

Introduction.- Terahertz Time-Domain Spectroscopy.- Rotatable-Polarisation Terahertz Time-Domain Spectroscopy of Anisotropic Media.- Scalable Interdigitated Photoconductive Emitters for the Electrical Modulation of Terahertz Beams With Arbitrary Linear Polarisation.- Tracking Disorder Broadening and Hysteresis in First-Order Phase Transitions via the Electromagnon Response in Improper Ferroelectrics.- High-Field Terahertz Time-Domain Spectroscopy of Single-Walled Carbon Nanotubes and CuO.- Conclusions.

O autorze

Dr. Desplat obtained a Master's degree in Condensed Matter and Nanophysics from the University of Strasbourg in 2015, followed by a PhD at the University of Glasgow, UK, which she defended in 2019. The last two years of her PhD were carried out at the Centre for Nanoscience and Nanotechnology, University of Paris-Saclay, France. In 2020, she started a position as a postdoctoral researcher at the Institut de Physique et Chimie des Materiaux de Strasbourg and the University of Strasbourg, France.

Blurb

The energy cost associated with modern information technologies has been increasing exponentially over time, stimulating the search for alternative information storage and processing devices. Magnetic skyrmions are solitonic nanometer-scale quasiparticles whose unique topological properties can be thought of as that of a Mobius strip. Skyrmions are envisioned as information carriers in novel information processing and storage devices with low power consumption and high information density. As such, they could contribute to solving the energy challenge.

In order to be used in applications, isolated skyrmions must be thermally stable at the scale of years. In this work, their stability is studied through two main approaches: the Kramers' method in the form of Langer's theory, and the forward flux sampling method. Good agreement is found between the two methods. We find that small skyrmions possess low internal energy barriers, but are stabilized by a large activation entropy. This is a direct consequence of the existence of stable modes of deformation of the skyrmion. Additionally, frustrated exchange that arise at some transition metal interfaces leads to new collapse paths in the form of the partial nucleation of the corresponding antiparticle, as merons and antimerons.