Terahertz Wave-Induced Spin-Switching Technology
ABOUT TWISST
Project Overview
This project brings together leading researchers from the UK and Germany to develop the scientific understanding needed to create a new generation of memory-devices characterised by very low energy consumption and switching times of one trillionth of a second. This requires the development of new devices capable of operating at corresponding frequencies called terahertz (THz - 10^12 Hz) i.e. thousand times faster than that used in current data communication and processing standards. Such very short pulses of electro-magnetic radiation are among the shortest stimuli available in science and technology and are made from light particles, photons, whose energies naturally match those of elementary quantum magnets, called “spins”. The THz excitation of the spins (THz spintronics) will be strong enough to induce switching of the spin orientation, representing the elementary act of writing a bit of information. As THz photons exactly match the excitation energy, this represents the optimally energy efficient switching regime, avoiding the localised heating that plagues current energy assisted data storage schemes.
The key idea behind the project is to develop THz spintronics both as broadband THz emitters and as a technology capable
of switching the magnetic state of a data storage element. The emitters will generate very strong pulses of THz radiation using emitters based on ultrathin layers of magnetic and non-magnetic metals. By exciting this system with an extremely short laser pulse (50 quadrillionths of a second), a transport of spins can be generated in the magnetic layer, which travels into the non-magnetic layer, resulting in the generation of an ultrashort burst of the electric current and the emission of a THz pulse. We will focus and concentrate this THz emission with an antenna onto another magnet, to switch a nanoscale magnetic bit. Our studies are expected to deliver unprecedented insights into the physics of light-magnetism interactions on extreme time and length scales while laying the fundament for the data storage technology of the future.
The project is expected to cement an enduring collaboration with the bilateral partners providing a framework for new directions in the field of THz technology and ultrafast magnetism and spintronics.
An EPSRC funded project - Award Number: UKRI1237
Team members
Dr. Darren Graham
Project Lead, The University of Manchester
Dr. Graham is the Head of Research in the Department of Physics and Astronomy. His research focuses on THz technology and its application. He has made substantial contributions to the development of THz spintronic devices. He serves on the advisory board for the EPSRC NetworkPlus in Terahertz Systems.
Dr. Morgan Hibberd
Project co-lead, The University of Manchester
Dr. Hibberd is a Research Fellow in the Department of Physics and Astronomy. He is a leading expert in THz spintronics. He has contributed significantly to the exploitation of spintronic THz emitters.
Prof. Steven Jamison
Project co-lead, Lancaster University
Prof. Jamison is in the Department of Physics and specialises in the use of ultrafast optical lasers to generate and detect single-cycle, sub-picosecond terahertz pulses through nonlinear processes. He acts as a co-lead for the Special Interest Group "Solid State and Quantum Materials, Devices and Systems" of the EPSRC NetworkPlus in Terahertz Systems.
Dr. Rostislav Mikhaylovskiy
Project co-lead, Lancaster University
Dr. Mikhaylovskiy is in the Department of Physics and specialises in the physics of light-magnetism interactions. His research focuses on exploiting terahertz pulses of light to study and control magnetisation dynamics. He has recently been awarded a Green Future Fellowship from the Royal Academy of Engineering to develop energy efficient magnetic memory of the future.
Dr. Paul Nutter
Project co-lead, The University of Manchester
Dr. Nutter is in the Department of Computer Science and his research focuses on thin magnetic films traditionally used for data storage applications. He has worked on the
analysis of the readout process in optical, magneto-optical and magnetic data storage, as well as looking at data recovery processes in these systems.
Prof. Tom Thomson
Project co-lead, The University of Manchester
Prof. Thomson is a leading member of the UK magnetism and spintronics community with research interests in thin film magnetism for THz spintronics, data storage, van der Waals systems and in novel magnetically ordered alloys. He is a member of the senior leadership team of the IEEE Magnetics Society and is responsible for bringing the largest annual conference in the field to Manchester in 2026 (Intermag 2026).
Join us
PhD studentships
If you are interested in working with the TWISST team then please contact us in the first instance. We normally have fully-funded PhD studentships, which include a stipend to support living expenses.
Research Associate Jobs
Research Associate in Terahertz Spintronic Emitters - Closing date 19th March 2026
Job reference: SAE-030990
Department of Physics and Astronomy, University of Manchester
Salary: £37,694 - £41,064 per annum, depending on relevant experience
Contract Duration: 24 months
A postdoctoral Research Associate position is available to undertake research in a UKRI/EPSRC funded research project to investigate the development of terahertz (THz) spintronic emitters as strong sources of THz radiation and for supporting the switching of nanoscale magnetic bits at THz timescales. The work is experimental in nature and focuses on development of future storage technologies offering low energy, but high-speed magnetic switching.
Publications
Enhancing the emission from trilayer spintronic terahertz emitters by Cu alloying
C. Bull, R. Ji, T. A. Gething, B. F. Spencer, T. Thomson, D. M. Graham, and P. W. Nutter
AIP Advances 16, 025341 (2026), DOI: 10.1063/9.0001020
We report on strategies to optimize the amplitude of THz electric fields from spintronic emitters. Specifically, we explore the effect of Cu alloying on the emission from trilayer, W/CoFeB/Pt, emitters. By introducing Cu into both the W and Pt layers we show a significant increase in emission of ∼27% compared to a trilayer without Cu, and an increase of ∼61%compared to a CoFeB/Pt bilayer emitter. These results demonstrate significant potential for improved THz emission by optimizing the metallic layer by alloying with Cu.
THz-driven spin dynamics in orthoferrites with Kramers and Non-Kramers rare-earth ions
R. A. Leenders, O. Y. Kovalenko, Y. Saito, N. R. Vovk, A. V. Kimel, and R. V. Mikhaylovskiy
Phys. Rev. Lett. 135, 246703 (2025), DOI: 10.1103/ldnx-67qz
Using an intense THz pulse to drive spin dynamics, we investigated its effect on the magnetization steering angle in two similar magnetic materials with different electronic orbitals. After exciting the magnet and subsequently analysing its magnetic state, we found that interaction between orbital motion and spinning enables a 10-fold larger spin deflection by the THz pulse than the one without such interactions.
Theory of terahertz-driven magnetic switching in rare-earth orthoferrites: The case of TmFeO3
N. R. Vovk, E. V. Ezerskaya, and R. V. Mikhaylovskiy
Phys. Rev. B 111, 064411 (2025), DOI: 10.1103/PhysRevB.111.064411
Antiferromagnetic iron oxides with rare-earth ions provide a promising platform for ultrafast spin switching by light. The magnetic properties in these materials are defined by anisotropic exchange coupling between the rare-earth orbitals and iron spins. Here, we presented a comprehensive theory, describing the dynamical response of the magnetic rare-earth and iron systems to a strong ultrashort THz pulse. Working out the case of the archetypical orthoferrite TmFeO3, we identified different coherent spin switching scenarios in this compound.
The paper is highlighted as an Editors’ Suggestion
Canted spin order as a platform for ultrafast conversion of magnons
R. A. Leenders, D. Afanasiev, A. V. Kimel and R. V. Mikhaylovskiy.
Nature 630, 335 (2024), DOI: 10.1038/s41586-024-07448-3
Practical applications of magnonic circuits require elements mimicking the work of a transistor, allowing for nonlinear control of one magnon by another magnon (e.g. for amplification). Demonstrating such nonlinearities in antiferromagnets has been a monumental challenge. In this work we addressed this challenge and showed the generation of sub-THz frequency and nanoscale magnons resulting from a nonlinear magnon-magnon interaction mediated through photons. The magnons were excited by the two laser pump pulses, delayed with respect to each other, allowing for observing magnon conversion directly in the time domain.
Tunable multi-cycle terahertz pulse generation from a spintronic emitter
Ji, R., Hibberd, M. T., Lin, C. H., Walsh, D. A., Thomson, T., Nutter, P. W., and Graham, D. M.
Applied Physics Letters 123, 212402 (2023), DOI: 10.1063/5.0176314
We demonstrate that a spintronic terahertz (THz) emitter can be driven by a chirped-pulse beating scheme to generate narrowband THz pulses, with continuous tuning of the frequency and linewidth by simply adjusting the laser chirp and the time delay between chirped pulses. Our proof-of-concept results pave the way to future narrowband THz sources with subgigahertz linewidth and center frequencies continuously tunable from 0.1 to 30 THz.
Spintronic terahertz emitters exploiting uniaxial magnetic anisotropy for field-free emission
and polarization control, Hewett, S., Shorrock, A., Lin, C.-H., Ji, R., Hibberd, M., Thomson, T., Nutter, P., and Graham, D. Applied Physics Letters 120, 122401 (2022), DOI: 10.1063/5.0087282
We identify an in-plane uniaxial magnetic anisotropy (UMA) in the ferromagnetic layer of CoFeB/Pt spintronic structures. By maximizing the UMA during the film deposition process we develop CoFeB/Pt spintronic structures that can emit broadband THz pulses without the need for an applied magnetic field and show that the linear polarization plane of the emitted THz radiation can be manipulated by changing the magnitude of an applied field, demonstrating THz polarization control.
Spintronic terahertz emitters: Status and prospects from a materials perspective
Bull, C., Hewett, S. M., Ji, R., Lin, C.-H., Thomson, T., Graham, D. M. and Nutter, P. W.,
Applied Physics Letters Materials 9, 090701 (2021), DOI: 10.1063/5.0057511
Spintronic terahertz (THz) emitters, consisting of ferromagnetic (FM)/non-magnetic (NM) thin films, have demonstrated remarkable potential for use in THz time-domain spectroscopy and its exploitation in scientific and industrial applications. In this review, we present a comprehensive overview of the experimental and theoretical findings that have led to the development of spintronic THz emitters, which hold promise for use in a wide range of THz applications. We summarize the current understanding of the mechanisms that contribute to the emission of THz radiation from the spintronic heterostructures and explore how the material properties contribute to the emission process.
Temporal and spectral fingerprints of ultrafast all-coherent spin switching
S. Schlauderer, C. Lange, S. Baierl, T. Ebnet, C. P. Schmid, D. C. Valovcin, A. K. Zvezdin, A. V. Kimel, R. V. Mikhaylovskiy and R. Huber.
Nature 569, 383 (2019), DOI: 10.1038/s41586-019-1174-7
In this work we reported all-coherent spin switching in an antiferromagnet by an intense THz pulse, achieving record low energy dissipation of 1 µeV per spin. We fabricated a microscale antenna on a surface of the sample, which strongly concentrated and thus enhanced the terahertz radiation. With this structure, the force on the spins exerted by the terahertz pulses was strong enough to change the structure’s magnetic orientation within just a few picoseconds.
Magnetic-field tailoring of the terahertz polarization emitted from a spintronic source
Hibberd, M. T., Lake, D. S., Johansson, N. A. B., Thomson, T., Jamison, S. P., and Graham, D. M.,
Applied Physics Letters 114, 031101 (2019), DOI: 10.1063/1.5055736
We demonstrate a method to create arbitrary terahertz (THz) polarization profiles by exploiting the magnetic field-dependent emission process of a spintronic source. As a proof-of-concept, we show that by applying a specific magnetic field pattern to the source, it is possible to generate a quadrupole-like THz polarization profile. This unique ability to generate any desired THz polarization profile opens up possibilities for schemes such as rotatable polarization spectroscopy and for efficient mode coupling in various waveguide designs.
Collaborative facilities
The TWISST team is open to collaborative research, especially with UK and German academic institutions, and industry. Contact us if you are interested in using any of our facilities.
At Manchester
Asynchronous optical sampling (ASOPS) facility combines two ultrafast Ti:Sapphire laser systems with a stabilisation unit and a fast acquisition card. The facility enables high-speed terahertz time domain spectroscopy (THz-TDS) by replacing the slow mechanical delay stage typically used in THz-TDS systems. This high-speed capability is ideal for studying rapid changes in materials.
The facility is driven by the ASOPS Engine from Novanta Photonics. Each Ti:Sapphire oscillator (model: Taccor power 6) delivers sub-30 femtosecond pulses at a central wavelength of 800 nm, operates at a repetition rate of 1 GHz and outputs an average power of over 1 W.
For more information contact Darren Graham
At Lancaster
We have two ultrafast amplified laser systems (both 7 mJ pulse energy, 1 kHz repetition rate, ~100 fs pulse duration, 800 nm central wavelength). Using these lasers combined with optical parametric amplifiers (OPA) and non-collinear difference frequency generator (NDFG), we have capability to generate intense pulses (electric/magnetic peak field 1 MV/cm and 0.3 Tesla respectively) of THz frequencies (broadband spectrum 0.1 – 2.5 THz) and infrared/visible wavelengths (narrowband, continuously tuneable between 250 nm – 18 µm). We have custom-built non-collinear optical parametric amplifier (NOPA) yielding ultrashort pulses of ~10 fs, enabling sub-cycle electro-optic sampling of mid-infrared fields. The existing cryogenic equipment allows for the pump-probe measurements in a broad temperature range 3.5 – 400 K. We study ultrafast dynamics and switching in a broad variety of samples including ferromagnetic metals, spintronic heterostructures, antiferromagnetic oxides, and even quantum superfluids.
For more information contact Rostislav Mikhaylovskiy
