University of Exeter Scientists Achieve Breakthrough in Harnessing Heat to Control Magnetism in 2D Materials

By Duncan Sandes, University of Exeter

Pioneering new research could help unlock exciting new potential to create ultrafast, laser-driven storage devices.

Groundbreaking research, led by experts from the University of Exeter, would revolutionize the field of data storage, through the development of laser-driven magnetic domain memories.

The new research is based on creating a pivotal new method for using heat to manipulate magnetism with unprecedented precision in 2D van der Waals materials.

Typically, heat is an unwanted byproduct of power consumption in electronic devices, especially in semiconductors. As devices become smaller and more compact, managing heat has become one of the major challenges in modern electronics.

However, this new research turns this challenge into an opportunity. The team’s innovative technique leverages the unique properties of 2D materials, where the weak interlayer bonds allow for exceptionally low thermal conductivity and highly anisotropic heat dissipation.

The research, led by Dr Maciej Dąbrowski, University of Exeter, introduces a novel approach to controlling heat flow and magnetic properties on timescales as short as hundreds of femtoseconds (10^-15 seconds).

By using carefully timed laser pulses of specific wavelengths to heat the material, followed by the use of pulses at another wavelength to probe the resulting changes, the team achieved real-time monitoring of temperature and magnetization dynamics in atomically thin 2D materials.

This allowed for sub-picosecond temporal resolution and sub-micron spatial resolution, setting a new benchmark for precision in this field.

A key breakthrough of the research was the team’s ability to manipulate the thickness of the magnetic layers, significantly enhancing the rate at which heat dissipates and accelerating the magnetization recovery process.

These advancements lay the foundation for the development of ultrafast data recording devices that operate exclusively with laser pulses, entirely eliminating the need for external magnetic fields.

The potential applications of this breakthrough are vast. The ability to control magnetism with laser pulses, without the need for external magnetic fields, could enable the creation of highly efficient, non-volatile memory devices that are faster, smaller, and more reliable than anything currently available.

Dr. Dąbrowski said: “This research opens up exciting possibilities for thermal engineering of future devices on the ultrafast timescale. Robust magnetic domain memory effect observed in our results has so far been unreachable in other materials and reveals new applications of 2D van der Waals magnets in ultrafast magnetic recording and quantum technologies based on the spin of the electron.”

Article: Ultrafast thermo-optical control of spins in a 2D van der Waals semiconductor

Nature Communications has published an article written by Maciej Da̧browski, Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK, Sumit Haldar, Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK, Safe Khan, London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WCH1 0AH, UK, Paul S. Keatley, Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK, Dimitros Sagkovits, Zekun Xue, Charlie Freeman, London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WCH1 0AH, UK, Ivan Verzhbitskiy, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore, Theodor Griepe, Unai Atxitia, Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049, Madrid, Spain, Goki Eda, Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117542, Singapore, Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore, and Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore, Hidekazu Kurebayashi, London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London, WCH1 0AH, UK, Department of Electronic & Electrical Engineering, UCL, London, WC1E 7JE, UK, and WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1, Katahira, Sendai, 980-8577, Japan, Elton J. G. Santos, Institute for Condensed Matter Physics and Complex Systems, School of Physics and Astronomy, The University of Edinburgh, Edinburgh, EH9 3FD, UK, Higgs Centre for Theoretical Physics, University of Edinburgh, Edinburgh, UK, and Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Basque Country, Spain, and Robert J. Hicken, Department of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK.

Abstract: “Laser pulses provide one of the fastest means of manipulating electron spins in magnetic compounds and pave the way to ultrafast operation within magnetic recording, quantum computation and spintronics. However, effective management of the heat deposited during optical excitation is an open challenge. Layered two-dimensional (2D) van der Waals (vdW) materials possess unique thermal properties due to the highly anisotropic nature of their chemical bonding. Here we show how to control the rate of heat flow, and hence the magnetization dynamics, induced by an ultrafast laser pulse within the 2D ferromagnet Cr₂Ge₂Te₆. Using time-resolved beam-scanning magneto-optical Kerr effect microscopy and microscopic spin modelling calculations, we show that by reducing the thickness of the magnetic layers, an enhancement of the heat dissipation rate into the adjacent substrate leads to a substantial reduction in the timescale for magnetization recovery from several nanoseconds down to a few hundred picoseconds. Finally, we demonstrate how the low thermal conductivity across vdW layers may be used to obtain magnetic domain memory behaviour, even after exposure to intense laser pulses. Our findings reveal the distinctive role of vdW magnets in the ultrafast control of heat conduction, spin dynamics and non-volatile memory.“