Observing, Creating and Addressing Topological Spin Textures in a Monolayer XY Magnet

点击翻译按钮获取中文摘要

Magnetism has only recently (2017) been observed in a strictly two-dimensional material. Magnetic order in two-dimensions has been at the heart of many long-standing queries in condensed matter physics, particularly in relation to the absence /presence of long-range structural, electronic and magnetic order, the influence of dimensionality on order/disorder transition, and the connection between topology and solid-state materials.Magnetic monolayers have recently been synthesised at the University of Nottingham, offering an experimental platform to study both theoretical concepts surrounding two-dimensional physics and develop new technologies built on these materials. Yet, to date, many of these monolayer magnetic materials have not been characterised at the atomic-scale. This means that the impact of local structural and electronic disorder on the global or macroscopic magnetic properties has not yet been established. This connection, a correlation between atomic-scale and macroscopic properties is the primary aim of this Ph.D. studentship.The only tool capable of this scientific endeavour is the scanning tunnelling microscope. Its ability to characterise structural and electronic properties at the atomic-scale, in addition to its ability to map spin or magnetic moments at the atomic-scale, make it the perfect tool for this project. The University of Nottingham has recently commissioned a low-temperature scanning tunnelling microscope capable of measuring in magnetic fields, which enables a complete characterisation of magnetic materials.This instrument is currently cooled with liquid helium and consumes roughly 100 litres per week, this translates to roughly £80,000 per year in operational costs. Cryogenic designed and manufactured this cryostat and is developing a recovery and reliquification system to solve this issue. In addition to significantly reducing the system's operating costs, the liquefier from Cryogenic would allow for continuous 24/7 operation of the STM for years at a time, while measurements are currently disrupted every seven days to refill cryogens. A significant part of the Ph.D. project will be to work with the company to install and design such a system to minimise its impact on the performance of the scanning tunnelling microscope. A working helium collection and reliquification facility will provide a game-changing development for the long-term use of this tool for the investigation of magnetic materials.