Skyrmionics: From Magnetic Excitations to Functioning Low-Energy Devices

Lead Research Organisation: Durham University
Department Name: Physics

Abstract

Tony Skyrme proposed that under special circumstances it is possible to stabilize vortex-like whirls in fields to produce topologically stable objects. This idea, effectively of creating a new type of fundamental particle, has been realised with the recent discovery of skyrmions in magnetic materials. The confirmation of the existence of skyrmions in chiral magnets and of their self-organization into a skyrmion lattice has made skyrmion physics arguably the hottest topic in magnetism research at the moment. Skyrmions are excitations of matter whose occurrence and collective properties are mysterious, but which hold promise for advancing our basic understanding of matter and also for technological deployment as highly efficient memory elements. Following the discovery of skyrmions in a variety of materials, several urgent questions remain which are holding back the field: what are the general properties of the phase transitions that lead to the skyrmion lattice phase, the nature of its structure, excitations and stability and how might we exploit the unique magnetic properties of this matter in future devices? These questions have only recently begun to be addressed by several large international consortia and are far from being resolved. For the UK to contend in this highly competitive field a major project is required that brings together UK experts in materials synthesis and state-of-the-art theoretical and experimental techniques. We propose the first funded UK national programme to investigate skyrmions, skyrmion lattices and skyrmionic devices. Our systematic approach, combining experts from different fields is aimed at answering basic questions about the status of magnetic skyrmions and working with industrial partners to develop technological applications founded on this physics.

Planned Impact

{Knowledge impact: scientific}
Our research will generate immediate and significant cross-disciplinary impact that will benefit physicists, chemists and materials scientists studying magnetism, the wider community of many-body quantum mechanics and topological physics, and the areas of technological applications of magnetism and materials simulation. We are especially excited that this will impact across disciplines, enabling us to extend our research to those in the areas of materials discovery, thin film growth, topological physics and technological development.

{Knowledge impact: technical}
We will work towards the design of a skymionic device that will open up prospects for ultra-low power information and storage technologies. This will address the ever-increasing demands for processing and storing extraordinarily large amounts of data. Current spintronic devices work by reversing the magnetic ordering within micron-sized ferromagnetic domains. Skyrmions are of size 10 - 100 nm and are remarkably mobile. They can be created, transported and manipulated by electric and magnetic fields. Electrical current densities of 10^6 Am^-2 can cause skyrmion motion, which compares with 10^11 Am^-2 required to move ferromagnetic domains. Skyrmions therefore represent a potential route to high-density, low-energy magnetic storage and the smallest micromagnetic configuration objects for novel ultra low-power magnetoelectrical devices. We aim to develop skyrmionic materials towards the point of deployment in device applications in collaboration with our industrial partners. Also key to our proposal is the development and use of state-of-the-art measurement technologies and theoretical techniques. Working closely with industry we will align our scientific programme with the engineering and commercial realities of modern-day information technologies.

{Economic impact and IP}
The potential economic impact of skyrmionics is enormous. Ultra high density magnetic storage and low energy magnetic sensors could result from our research. IP generated in fields such as magnetic devices and information processing/computing will be identified and protected with the assistance of the knowledge transfer services from the institutions involved.

{People and training}
A project of this scale which involves significant staff time provides an opportunity to exploit a powerful and varied platform for training. This will centre around the cohort of PDRAs, who will be trained in a variety of state-of-the-art experimental and theoretical techniques including crystal and film growth, physical characterization and experimentation, theoretical modelling and industrial work. Each will benefit from the diverse range of techniques we will employ as part of the project and also from the range of working environments involved. Senior PDRAs will play a role in mentoring junior colleagues and supervising the work of PhD students. The PDRAs will manage and organise internal project meetings and seminars along with writing an electronic project newsletter and blog on the project website.

{Outreach}
Topological objects are not limited to skyrmions, but include domain walls (used in memory applications), vortices (used in superconducting devices) and monopoles (thought to exist in the early Universe). These are of increasing importance in modern science and technology but are relatively unexplored in the classroom, despite the fact that they are most easily explained with pictures rather than sophisticated mathematics. We will initiate an outreach effort as part of this project combining workshops for Key Stage 3 students along with an outreach website aimed at the established web-based community of popular science enthusiasts. Our outreach project aims to introduce the ideas of topological physics to a broad audience and stress its great potential for applications in future technologies.

Publications

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Description Members of the Skyrmion project have discovered a method of measuring the topological charge, or winding number, of topological objects such as Skyrmions using polarised x-rays
Exploitation Route A new way to experimentally determine the topological winding number of a system has been discovered
The elegant mathematical concept of topology generally describes a system's protected symmetry, which cannot be captured by the well-established symmetry-breaking theories. Driven by the enormous success of topological insulators and magnetic skyrmions, topologically protected materials are at the centre of attention. However, until now, the experimental determination of topological properties of materials was very indirect, and heavily relying on theoretical modelling in support of the experimental data. In a recent article in Nature Communications, scientists report on a new general physical principle that allows direct access to the topological property of materials.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Energy

URL http://www.diamond.ac.uk/Science/Research/Highlights/2017/topological-knots.html
 
Description Participation in Science Festival Durham for School children Participation in Celebrate Science festival for children and families Saturday Morning Science Lecture for Children and families
Sector Education
Impact Types Cultural,Societal