Harnessing the power of topology in oxide electronics for future IT components

Lead Research Organisation: University of Oxford
Department Name: Oxford Physics

Abstract

In spite of its extraordinary success in fuelling the IT revolution, silicon (CMOS) technology is intrinsically not energy-efficient, because it relies on the movement of electrical charge, which is associated with Joule heating. One of the front runners among 'beyond-CMOS' technologies is spintronics, which relies on spins rather than charges to transfer and process information; however, much of the energy efficiency of spintronics is lost if spin flipping - the elementary spintronic operation - must in itself be performed by electrical currents. For this reason, voltage control of magnetic components is widely considered to be the key to large-scale commercialisation of spintronics [1-3]. The field of oxide electronics emerges precisely from the consideration that oxides, especially those containing magnetic transition metal ions such as Co, Mn and Fe, can display a multitude of intriguing electrically-controlled multi-functional properties in their insulating states, whilst integration with CMOS is already a reality. The potential of oxide electronics can be further enhanced by exploiting the power of topology, which involves, quite literally, tying spins into 'magnetic knots'. In work recently published in Nature Materials [4], an international team of collaborators lead by Professor Paolo G. Radaelli (Oxford Physics) presented a major breakthrough in this field [5]: they created, for the first time, small-scale hybrid oxide/metal topological magnetic objects, consisting of tightly-coupled spin vortices in antiferromagnetic iron oxide (a-Fe2O3) and ferromagnetic metallic cobalt (Co). One particularly appealing feature of this system is that it employs cheap and readily available materials (a-Fe2O3 is the most abundant constituent of common rust!) and relatively simple fabrication, raising hopes that these systems could be deployed on a commercial scale in the future. This EPSRC-funded DPhil project will give the successful candidate the opportunity to develop this line of research in different directions, both fundamental and applied.
This project falls under the EPSRC Quantum devices components and systems theme.

Publications

10 25 50
publication icon
Jani H (2021) Antiferromagnetic half-skyrmions and bimerons at room temperature. in Nature

publication icon
Harrison J (2022) Route towards stable homochiral topological textures in A -type antiferromagnets in Physical Review B

 
Description I have pushed the techniques available for studying the magnetic textures observable in alpha-Fe2O3, which are potential data carriers in next-generation post-CMOS computing devices, into the spaced of transmission-based x-ray measurements. This has allowed for in-situ investigations of the effects of temperature, strain and magnetic fields that were previously not available for experimental studies in electron emission based measurements. A reasonable number of advancements were needed to make these techniques work, some developed by my collaborators and some, primarily the development of masks for holography experiments, have undergone a number of failed trials and iterations in order to create viable workable versions. These investigations are ongoing but will be critical to the studies needed to advance antiferromagnetic topological texture based computing from an initial concept to a workable solution.

My micromagnetic models have opened up a set of future experiments by highlighting new topological texture types and phenomenology we could explore given reasonable material and heterostructure engineering. Several of these experimental routes are under experimental investigation at the time of writing and could lead to advancements towards antiferromagnetic topological texture based computing devices.
Exploitation Route Many of the technical advancements made to allow for synchrotron based transmission measurements of our antiferromagnetic films are applicable to a number of other material systems and we are currently exploring a number of other potential materials that either I or our collaborators could use these techniques to investigate.

My micromagnetic models are applicable to all A-type antiferromagnets, a material class abundant in nature and under extensive investigation across several fields, allowing them to hopefully be useful to many other research groups to aid in their own investigations of magnetic properties of these materials.
Sectors Digital/Communication/Information Technologies (including Software),Electronics
 
Title Micromagnetic model for A-type antiferromagnets 
Description I created a micromagnetic model based on the open-source code MuMax3 (https://mumax.github.io/) to study magnetic textures in A-type antiferromagnets such as alpha-Fe2O3, the key system for the majority of our experimental work. This allows me to accurately model the various magnetic interactions present in the system in order to determine the stability and scaling behaviour of the critical topological textures that are observed in our experimental work. 
Type Of Material Computer model/algorithm 
Year Produced 2022 
Provided To Others? Yes  
Impact This work not only provides a platform for independently verifying our experimental results, but also to predict new behaviour such as the stabilisation of the long sought-after antiferromagnetic skyrmions which we have predicted should be stable in alpha-Fe2O3 if we can induce a reasonable Dzyaloshinskii-Moriya interaction. This model is also applicable to general A-type antiferromagnets, potentially giving it a scope beyond our research to other groups studying magnetic phenomena in similar systems.