Magnetic writing in nanostructured arrays
Lead Research Organisation:
Imperial College London
Department Name: Physics
Abstract
One of the main research interests of the functional magnetism group is the magnetic properties of nanostructured materials and devices. We have an interest in magnetic nanostructured arrays that are usually called Artificial Spin Ice. We have recently developed a method of writing any magnetic pattern we choose into these magnetic arrays using a magnetic force microscope.1,2 The aim of this project will be to fabricate artificial spin Ice structures and to use the writing technique to explore the possibilities for two new types of computation. One of these, known as a neural network, is a massively parallel computation based on the collective response of the whole network. The other, known as magnonics3, relies on manipulating spin waves (magnons) within the structures. Ferromagnetic resonance, or FMR, is a standard tool used for probing spin waves and spin dynamics in ferromagnetic materials. FMR arises from the precessional motion of the magnetization of a ferromagnetic material in an external magnetic field.
[1] Testing and training the 'neural network' response from different starting configurations.
[2] Testing the FMR with different array geometry and starting configuration and optimising for magnonics.
1J.C. Gartside, D.M. Arroo, D.M. Burn, V.L. Bemmer, A. Moskalenko, L.F. Cohen and W.R. Branford, Realising the kagome ice ground state and thermally inaccessible states via topological defect-driven magnetic writing. Nature Nanotechnology: Accepted for publication (2017). (Preprint at https://arxiv.org/abs/1704.07439)
2J.C. Gartside, D.M. Burn, L.F. Cohen and W.R. Branford, A novel method for the injection and manipulation of magnetic charge states in nanostructures. Scientific Reports. 6: 32864 (2016).
3D. Grundler, Reconfigurable magnonics heats up. Nature Physics. 11: 438-441 (2015).
[1] Testing and training the 'neural network' response from different starting configurations.
[2] Testing the FMR with different array geometry and starting configuration and optimising for magnonics.
1J.C. Gartside, D.M. Arroo, D.M. Burn, V.L. Bemmer, A. Moskalenko, L.F. Cohen and W.R. Branford, Realising the kagome ice ground state and thermally inaccessible states via topological defect-driven magnetic writing. Nature Nanotechnology: Accepted for publication (2017). (Preprint at https://arxiv.org/abs/1704.07439)
2J.C. Gartside, D.M. Burn, L.F. Cohen and W.R. Branford, A novel method for the injection and manipulation of magnetic charge states in nanostructures. Scientific Reports. 6: 32864 (2016).
3D. Grundler, Reconfigurable magnonics heats up. Nature Physics. 11: 438-441 (2015).
Organisations
Publications
Gartside J
(2020)
Current-controlled nanomagnetic writing for reconfigurable magnonic crystals
in Communications Physics
Stenning K
(2020)
Magnonic Bending, Phase Shifting and Interferometry in a 2D Reconfigurable Nanodisk Crystal
in ACS Nano
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| EP/N509486/1 | 01/10/2016 | 31/03/2022 | |||
| 2120558 | Studentship | EP/N509486/1 | 01/10/2018 | 30/06/2022 | Kilian STENNING |
| EP/R513052/1 | 01/10/2018 | 30/09/2023 | |||
| 2120558 | Studentship | EP/R513052/1 | 01/10/2018 | 30/06/2022 | Kilian STENNING |
| Description | The adverse effects of continual shrinkage of transistor size such as excess heating, as well as the inefficiencies of commercial computational architecture is driving research to discover and develop novel computational architectures. A promising candidate for such architectures are reconfigurable arrays of nanomagnets whose dynamics operate in the GHz range. Nanomagnetic arrays comprise a network of strongly-interacting nanomagnetic elements which may be arranged in a variety of magnetic configurations (microstates). Access to arbitrary microstates has been historically challenging until a development in 2018 from our group allowed access to the entire microstate space by scanning a high moment tip across the surface of a nanomagnet to 'write' the magnetisation. The focus of the award is to utilise direct magnetic writing of nanostructured arrays to achieve novel functionality, with a focus on developing computational devices. The first outcome of the award was the development of a proposed scheme for current controlled nanomagnetic writing. In this scheme, a magnetic domain wall is driven by a current passing through the wire which leads to selective reversal of any arbitrary nanomagnet, improving both the speed of writing and the scalability of the system. Changing the microstate of the system is leveraged to achieve modulation of rf dynamics in the GHz range. The second discovery utilised the writing scheme on a circular shaped nanodisk. The novelty of this system is that a nanodisk can exist in two distinct magnetic states with vastly different inter-element coupling behaviours. Firstly, writing protocols were developed to allow access to both of these states across a wide range of nanodisk dimensions within an array. Here, microstate access was utilised to create active and inactive channels in any arbitrary direction across a 2D network capable of propagating and processing information encoded in excitations of the magnetisation. The proposed scheme is the first to demonstrate the potential of nanodisk systems, opening plentiful routes for designing reconfigurable computational devices. The previous schemes utilised nanomagnetic writing of a single nanoelement, which is unsuitable for large scale systems possibly required by experimental tecnhiques. As such, the final outcome so far is the development of a mm scale modified nanomagnetic array capable of accessing long-range ordered microstates which can then be probed by bulk experimental techniques. Different global field protocols allow access to a variety of states. The high frequency dynamics of these states were then probed to reveal distinct resonant spectra. |
| Exploitation Route | Reconfigurable nanomagnetic arrays are a promising candidate for ultra-low power computation. The outcomes of this funding have demonstrated a variety of fundamental properties such as waveguiding, gating and logic as well as tuneable high frequency dynamics, all of which are achieved by nanomagnetic writing of individual nanoelements. These outcomes provide a toolset for designing reconfigurable computational architectures for Boolean and unconventional computing where nanomagnets can both store and process information at the same time. In the short term, others may use the aforementioned outcomes to further explore nanomagnetic computational schemes. Furthermore, the current experimental writing technique is overly-slow in comparison with the system dynamics. As such, the continual development of nanosecond timescale writing will compliment the discovered functionality, allowing nanomagnetic arrays to become competitive with current device architectures. In the long term, others may use the results to develop an all-nanomagnetic computer operating at ultra-low power. |
| Sectors | Digital/Communication/Information Technologies (including Software) |
| URL | https://scholar.google.com/citations?user=-KoWyiUAAAAJ&hl=en&oi=ao |