TOHOKU UNIVERSITY Researchers

Education 3

Imperial College London　Department of Physics　Advanced Chracterisation of Materials Cerntre for Doctoral Training

2016/09 - 2020/11
UCL　London Centre for Nanotechnology　Advanced Characterisation of MAterials Centre for Doctoral Training

2016/09 - 2020/11
The University of Leeds　Department of Physics　Integrated Masters in Physics

2010/09 - 2014/07

Research Interests 12

Kapitza pendulum
dynamic stability
isotropic magnet
reservoir computing
machine learning
ferromagnetic resonance
mumax3
micromagnetic simulation
spin waves
magnonics
artificial spin ice
nanomagnetism

Research Areas 3

Natural sciences / Magnetism, superconductivity, and strongly correlated systems / magnetisation dynamics
Natural sciences / Magnetism, superconductivity, and strongly correlated systems / nanomagnetism
Nanotechnology/Materials / Material fabrication and microstructure control / artificial spin ice

Awards 3

Excellent Poster Award

2025/05　Institute of Materials Research, Tohoku University　Ultrastrong magnon-magnon coupling and chiral spin-texture control in a dipolar 3D multilayered artificial spin-vortex ice
JSPS Summer Program

2018/06　Japan Society for the Promotion of Science　Non-reciprocal spinwaves in inversion broken artificial nanomagnets
Best Presentation at ACM-CDT Summer Retread

Advanced Characterization of Materials Centre for Doctoral Training　Tunable Magnetisation Dynamics in Artificial Spin Ice via Shape Anisotropy Modification

Papers 12

Dynamical stability by spin transfer in nearly isotropic magnets

Hidekazu Kurebayashi, Joseph Barker, Takumi Yamazaki, Varun K. Kushwaha, Kilian D. Stenning, Harry Youel, Xueyao Hou, Troy Dion, Daniel Prestwood, Gerrit E. W. Bauer, Kei Yamamoto, Takeshi Seki

Nature Materials　25　2026/03/04
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41563-026-02510-z 　

ISSN： 1476-1122

eISSN： 1476-4660

More details Close

Abstract Spin transfer torques (STTs) control magnetization by electric currents, enabling a range of nano-scale spintronic applications. They can destabilize the equilibrium magnetization state by counteracting magnetic relaxation. Here we maximize the STT effect through a dedicated growth-annealing protocol for CoFeB thin films, such that magnetic anisotropies originating from the interface and shape almost cancel each other. The nearly isotropic magnets enable low-current dynamical stabilization of the magnetization in the direction opposite to an applied magnetic field, thereby realizing a spintronic analogue of the Kapitza pendulum. In an intermediate current regime, the STT drives large magnetization vector fluctuations that cover the entire Bloch sphere. The continuous variable associated with the stochastic magnetization direction may serve as a resource for probabilistic computing and neuromorphic hardware. Our results establish isotropic magnets as a platform to study as-yet-uncharted, far-from-equilibrium spin dynamics including anti-magnonics, with promising implications for unconventional computing paradigms.
Thickness dependence on dynamical spin injection driven by thermal effects in CoFeB/Pt bilayer

Sora Obinata, Troy Dion, Riku Iimori, Takashi Kimura

Scientific Reports　14　(1)　2024/12

DOI： 10.1038/s41598-024-75683-9 　

eISSN： 2045-2322
Ultrastrong magnon-magnon coupling and chiral spin-texture control in a dipolar 3D multilayered artificial spin-vortex ice

Troy Dion, Kilian D. Stenning, Alex Vanstone, Holly H. Holder, Rawnak Sultana, Ghanem Alatteili, Victoria Martinez, Mojtaba Taghipour Kaffash, Takashi Kimura, Rupert F. Oulton, Will R. Branford, Hidekazu Kurebayashi, Ezio Iacocca, M. Benjamin Jungfleisch, Jack C. Gartside

Nature Communications　15　(1)　2024/05/14
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41467-024-48080-z 　

eISSN： 2041-1723

More details Close

Abstract Strongly-interacting nanomagnetic arrays are ideal systems for exploring reconfigurable magnonics. They provide huge microstate spaces and integrated solutions for storage and neuromorphic computing alongside GHz functionality. These systems may be broadly assessed by their range of reliably accessible states and the strength of magnon coupling phenomena and nonlinearities. Increasingly, nanomagnetic systems are expanding into three-dimensional architectures. This has enhanced the range of available magnetic microstates and functional behaviours, but engineering control over 3D states and dynamics remains challenging. Here, we introduce a 3D magnonic metamaterial composed from multilayered artificial spin ice nanoarrays. Comprising two magnetic layers separated by a non-magnetic spacer, each nanoisland may assume four macrospin or vortex states per magnetic layer. This creates a system with a rich 16^N microstate space and intense static and dynamic dipolar magnetic coupling. The system exhibits a broad range of emergent phenomena driven by the strong inter-layer dipolar interaction, including ultrastrong magnon-magnon coupling with normalised coupling rates of $$\frac{\Delta f}{\nu }=0.57$$, GHz mode shifts in zero applied field and chirality-control of magnetic vortex microstates with corresponding magnonic spectra.
Ultrastrong Magnon-Magnon Coupling and Chiral Symmetry Breaking in a 3D Magnonic Metamaterial

Troy Dion, Killian Stenning, Alex Vanstone, Holly Holder, Rawnak Sultana, Ghanem Alatteili, Victoria Martinez, Mojtaba Kaffash, Takashi Kimura, Hidekazu Kurebayashi, will branford, Ezio Iacocca, M. Benjamin Jungfleisch, Jack C Gartside

2023/08/19

DOI： 10.21203/rs.3.rs-3123082/v1 　

More details Close

<jats:title>Abstract</jats:title> <jats:p>Strongly-interacting nanomagnetic arrays are ideal systems for exploring the frontiers of magnonic control. They provide functional reconfigurable platforms and attractive technological solutions across storage, GHz communications and neuromorphic computing. Typically, these systems are primarily constrained by their range of accessible states and the strength of magnon coupling phenomena. Increasingly, magnetic nanostructures have explored the benefits of expanding into three dimensions. This has broadened the horizons of magnetic microstate spaces and functional behaviours, but precise control of 3D states and dynamics remains challenging. Here, we introduce a 3D magnonic metamaterial, compatible with widely-available fabrication and characterisation techniques. By combining independently-programmable artificial spin-systems strongly coupled in the $\hat{z}$-plane, we construct a reconfigurable 3D metamaterial with an exceptionally high $16^N$ microstate space and intense static and dynamic magnetic coupling. The system exhibits a broad range of emergent phenomena driven by high-intensity inter-layer dipolar interaction, including ultrastrong magnon-magnon coupling with normalised coupling rates of $\frac{\Delta \omega}{\gamma} = 0.57$ and magnon-magnon cooperativity up to $C = 126.4$, GHz mode shifts in zero applied field and chirality-selective magneto-toroidal microstate programming and corresponding magnonic spectral control.</jats:p>
Reconfigurable training and reservoir computing in an artificial spin-vortex ice via spin-wave fingerprinting

Jack C Gartside, Kilian Stenning, Alex Vanstone, Holly Holder, Daan M. Arroo, Troy Dion, Francesco Caravelli, Hidekazu Kurebayashi, will branford

Nature Nanotechnology　2022/05

DOI： 10.1038/s41565-022-01091-7 　

ISSN： 1748-3387 1748-3395
Observation and control of collective spin-wave mode hybridization in chevron arrays and in square, staircase, and brickwork artificial spin ices

Troy Dion, Jack C Gartside, Alex Vanstone, Kilian Stenning, Daan M. Arroo, Hidekazu Kurebayashi, will branford

Physical Review Research　2022/02/11

DOI： 10.1103/physrevresearch.4.013107 　

ISSN： 2643-1564
Coupling microwave photons to topological spin textures in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>Cu</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mi>OSeO</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math>

Safe Khan, Oscar Lee, T. Dion, Christoph Zollitsch, S. Seki, Y. Tokura, Jonathan Breeze, Hidekazu Kurebayashi

Physical Review B　2021/09/03

DOI： 10.1103/physrevb.104.l100402 　

ISSN： 2469-9950 2469-9969
Reconfigurable magnonic mode-hybridisation and spectral control in a bicomponent artificial spin ice

Jack C Gartside, Alex Vanstone, Troy Dion, Kilian Stenning, Daan M. Arroo, Hidekazu Kurebayashi, will branford

Nature Communications　2021/05/03

DOI： 10.1038/s41467-021-22723-x 　

ISSN： 2041-1723

More details Close

<jats:title>Abstract</jats:title><jats:p>Strongly-interacting nanomagnetic arrays are finding increasing use as model host systems for reconfigurable magnonics. The strong inter-element coupling allows for stark spectral differences across a broad microstate space due to shifts in the dipolar field landscape. While these systems have yielded impressive initial results, developing rapid, scaleable means to access a broad range of spectrally-distinct microstates is an open research problem. We present a scheme whereby square artificial spin ice is modified by widening a ‘staircase’ subset of bars relative to the rest of the array, allowing preparation of any ordered vertex state via simple global-field protocols. Available microstates range from the system ground-state to high-energy ‘monopole’ states, with rich and distinct microstate-specific magnon spectra observed. Microstate-dependent mode-hybridisation and anticrossings are observed at both remanence and in-field with dynamic coupling strength tunable via microstate-selection. Experimental coupling strengths are found up to <jats:italic>g</jats:italic>/2<jats:italic>π</jats:italic> = 0.16 GHz. Microstate control allows fine mode-frequency shifting, gap creation and closing, and active mode number selection.</jats:p>
Magnonic Bending, Phase Shifting and Interferometry in a 2D Reconfigurable Nanodisk Crystal

Kilian Stenning, Jack C. Gartside, Troy Dion, Alexander Vanstone, Daan M. Arroo, Will R. Branford

ACS Nano　2021/01/26

DOI： 10.1021/acsnano.0c06894 　

ISSN： 1936-0851 1936-086X
Current-controlled nanomagnetic writing for reconfigurable magnonic crystals

Jack C Gartside, Son Gyo Jung, Seung Yeun Yoo, Daan M. Arroo, Alex Vanstone, Troy Dion, Kilian Stenning, will branford

Communications Physics　2020/11/30

DOI： 10.1038/s42005-020-00487-y 　

ISSN： 2399-3650

More details Close

<jats:title>Abstract</jats:title><jats:p>Strongly-interacting nanomagnetic arrays are crucial across an ever-growing suite of technologies. Spanning neuromorphic computing, control over superconducting vortices and reconfigurable magnonics, the utility and appeal of these arrays lies in their vast range of distinct, stable magnetization states. Different states exhibit different functional behaviours, making precise, reconfigurable state control an essential cornerstone of such systems. However, few existing methodologies may reverse an arbitrary array element, and even fewer may do so under electrical control, vital for device integration. We demonstrate selective, reconfigurable magnetic reversal of ferromagnetic nanoislands via current-driven motion of a transverse domain wall in an adjacent nanowire. The reversal technique operates under all-electrical control with no reliance on external magnetic fields, rendering it highly suitable for device integration across a host of magnonic, spintronic and neuromorphic logic architectures. Here, the reversal technique is leveraged to realize two fully solid-state reconfigurable magnonic crystals, offering magnonic gating, filtering, transistor-like switching and peak-shifting without reliance on global magnetic fields.</jats:p>
Tunable magnon-magnon coupling in synthetic antiferromagnets

A. Sud, Christoph Zollitsch, A. Kamimaki, Troy Dion, S. Khan, S. Iihama, S. Mizukami, H. Kurebayashi

Physical Review B　2020/09/10

DOI： 10.1103/physrevb.102.100403 　

ISSN： 2469-9950 2469-9969
Tunable magnetization dynamics in artificial spin ice via shape anisotropy modification

Dion, T., Arroo, D.M., Yamanoi, K., Kimura, T., Gartside, J.C., Cohen, L.F., Kurebayashi, H., Branford, W.R.

Physical Review B　100　(5)　2019

DOI： 10.1103/PhysRevB.100.054433

Show all ︎Show first 5

Misc. 2

Magnetic vortex writing and local reversal seeding in artificial spin-vortex ice via all-optical and surface-probe control

Holly Holder, Jack C. Gartside, Alex Vanstone, Troy Dion, Xiaofei Xiao, Kilian D. Stenning, Tingjun Zheng, Daniel Bromley, Tobias Farchy, Rupert F. Oulton, Will R. Branford

2025/05/22

More details Close

Artificial spin-vortex ice ('ASVI') is a reconfigurable nanomagnetic metamaterial consisting of magnetic nanoislands tailored to support both Ising macrospin and vortex textures. ASVI has recently shown functional applications including reconfigurable magnonics and neuromorphic computing, where the introduction of vortex textures broadens functionality beyond conventional artificial spin ice which generally supports macrospin states. However, local control of writing vortex states in ASVI remains an open challenge. Here we demonstrate techniques for field-free magnetic vortex writing in ASVI. We expand ASVI to support metastable macrospin, single-vortex and double-vortex states. All-optical writing via focused laser illumination can locally write double-vortex textures, and surface-probe writing using an MFM tip can locally write single vortex states. We leverage this writing to tailor and explore the reconfigurable energy landscape of ASVI, demonstrating programmable local seeding of avalanche-like reversal events. The global field-free texture selective writing techniques reported here expand the suite of nanomagnetic control techniques, with a host of future applications including fundamental studies of avalanche dynamics, physical memory, and direct writing of nanomagnetic 'weights' in physical neuromorphic neural networks.
Spin wave resonance in yttrium iron garnet stripe domains

Daniel Prestwood, Chris E. A. Barker, Kilian D. Stenning, Charlie W. F. Freeman, Tianyi Wei, Takashi Kikkawa, Troy Dion, Daniel Stoeffler, Yves Henry, Matthieu Bailleul, Noora Naushad, William Griggs, Thomas Thomson, Murat Cubukcu, Jack C. Gartside, Eiji Saitoh, Will R. Branford, Hidekazu Kurebayashi

2025/05/13

More details Close

We study a thin film yttrium iron garnet sample that exhibits magnetic stripe domains due to a small perpendicular magnetic anisotropy. Using wide-field magneto-optic Kerr effect measurements we reveal the domain pattern evolution as a function of applied field and discuss the role of the cubic anisotropy in the domain formation. Rich magnon spectra are observed in the stripe domain states, with a range of excitation conditions providing distinct spectra. The measurements are interpreted using micromagnetic simulations to provide the spatial profiles of each resonance mode. We further simulate domain patterns and resonance spectra accounting for the cubic anisotropy,with good correlation to experiment. This study highlights how non-collinear magnetic domain structures can host complex resonant behaviour in a low-damping magnetic material, with potential use in future magnonic applications.

Presentations 15

Magnetic Kapitza: Dynamic Stability in Nearly Isotropic Magnets via Spin Transfer Torque

Troy Dion

Iwate Spintronics SChool 2026　2026/03/03
A Brief History of Artificial Spin Ice: From Differential Fabrication to Application Invited

Troy Dion

IEEE AtC-AtG Magnetics Conference 2025　2025/11/18
Magnon Frequency Combing in Strongly Dipolar Coupled Magnetic Layers

Troy Dion

12th International Symposium on Metallic Multilayers (MML), Leeds, UK　2025/07/14
Ultrastrong magnon-magnon coupling and chiral spin-texture control in a dipolar 3D multilayered artificial spin-vortex ice

Troy Dion

148th IMR Lecture Meeting　2025/05/28
Ultrastrong magnon-magnon coupling and chiral spin-texture control in a dipolar 3D multilayered artificial spin-vortex ice Invited

Troy Dion

APS March Meeting, Anaheim、USA　2025/03/18
Microstate control and ultra-strong coupling in multi-layered artificial spin ice Invited

Troy Dion

Online Artificial Spin Ice (OASIS) Session 6　2024/10/28
Novel Artificial Spin Ice Geometries for Spintronics Applications

Troy Dion

Iwate Spintronics School　2024/02/14
Reconfigurable Spin-wave Dispersion in Continuous Magnetic Layer Induced via Artificial Spin Ice Magnonic Crystal

Troy Dion

Frontiers in Artificial Spin Ice
Reconfigurable Spin-wave Dispersion in Continuous Magnetic Layer Induced via Artificial Spin Ice Magnonic Crystal

Troy Dion

Intermag 2023 Sendai　2023/05/09
Reconfigurable Spin-wave Dispersion in Continuous Magnetic Layer Induced via Artificial Spin Ice Magnonic Crystal

Troy Dion

APS March Meeting, Las Vegas　2023/03/08
Reconfigurable Spin-wave Dispersion in Continuous Magnetic Layer Induced via Artificial Spin Ice Magnonic Crystal

Troy Dion

APS March Meeting, Las Vegas　2023/03/07
Collective Spin-wave Mode Hybridisation in Artificial Spin Ices

Troy Dion

International Colloquium on Magnetic Films and Surfaces, Okinawa　2022/07/12
Angular Dependent FMR of Rotational Symmetry Broken Artificial Kagome Spin Ice

Troy Dion

Advanced Characterization of Materials Conference, Barcelona　2019/07/10
Tunable Magnetization Dynamics in Artificial Spin Ice Via Shape Anisotropy Modification

Troy Dion

Institute of Physics Magnetism, Leeds　2019/04/08
Angular Dependent FMR of Rotational Symmetry Broken Artificial Kagome Spin Ice

Troy Dion

Institute of Physics Magnetism, Manchester　2018/04/09

Show all Show first 5

Research Projects 2

Spin-Wave Dynamics in Yytrium Iron Garnet / Nanomagnet Hybrid Devices for Magnonic Computing

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for JSPS Fellows

Institution: Kyushu University

2023/03/08 - 2024/03/31
マグノニック計算を目指したYIG/ナノ磁性体複合構造におけるスピンダイナミクス

木村崇, DION TROY

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 特別研究員奨励費

Institution: 九州大学

2020/11/13 - 2023/03/31

Teaching Experience 5

Science Debate Club　Kyushu University
International Science Special Lectures　Kyushu University
Postgraduate Teaching Assistant: Micromagnetic Simulation　Imperial College London
Postgraduate Teaching Assistant: Electronic and Electrical Engineering　UCL
A-Level Mathematics Tutoring　First Tutors