Shaken and stirred: Terahertz electric field control of magnetism

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The rapid move to wireless devices and the advent of cloud-based technologies in the 21st century’s digital economy call for denser, faster and more energy efficient data storage. However, the heat produced by modern data centres has already become a serious limitation to further increase their performance. At present, the data industry lacks a solution for this problem, which is expected to contribute greatly to the global warming and energy crisis in the near future. With MAGSHAKE I aim to pave the way towards a memory device characterized by very low energy consumption and switching times of one trillionth of a second. Very short pulses of electro-magnetic radiation at a terahertz (THz) frequency (i.e. thousand times faster than that in current data communication and processing standards) are among the shortest stimuli in condensed matter physics. These pulses are made from light particles (photons), with their energies naturally matching those of elementary quantum magnets, ‘spins’. These are used to store information in common magnetic hard disk drives. Hence, such THz photons can excite spins on their own energy scale without releasing any significant heat into the surrounding medium. MAGSHAKE will explore the manipulation of spins by a THz electric field, which can modulate the spin-orbit and exchange interactions which are responsible for magnetic ordering. These interactions are orders of magnitude stronger than the Zeeman energy due to an applied magnetic field. Therefore, the THz electric ‘shaking’ of the spins is expected to be strong enough to induce switching of the spins’ orientations, representing an elementary act of writing a bit of information. The proposed research programme aims to investigate the fundamentals of the electric field-driven nonlinear spin dynamics and to explore the basic requirements for the fastest and most energy-efficient spin switching in broad classes of magnetic materials.