Shaken, not stirred: a recipe for spin switching

For the first time, an international team of scientists demonstrates switching of magnetization by triggering the vibrations of crystal lattice. Their work is published in Nature Physics.

History tells us that small perturbations can have a profound effect on macroscopic systems; an unfortunate example being the collapse of the Broughton and Angers bridges in the mid-nineteenth century brought about by the (resonant) marching of soldiers in unison. Similarly, in condensed matter systems, small excitations can have large repercussions on both their ground and excited states.
The major question left open, however, is whether such excitations can be used for a constructive rather than destructive effect. Researchers from FELIX Laboratory and the University of Bialystok, in collaboration with scientists from the Institute for Molecules and Materials, Delft University of Technology and the Max Planck Institute for Solid State Research, have found a way to convincingly prove this.
The team has demonstrated that shaking atoms in a crystal for a short time can lead to a permanent switching of magnetization. Previous attempts focused on resonant pumping of phonon modes failed. For this excitation, researchers used the short and intense pulses from the free electron laser FELIX. It suited ideally to fit the resonance frequencies of the lattice. Following the excitation, nonlinear interactions in the phonon system change the potential landscape of the magnetic system forcing the latter to evolve into a peculiar four-domain pattern. "It has been discussed for years that such switching in principle could be possible, but has only now been realized, thanks to the high intensity and narrow bandwidth of the FELIX pulses", explains professor Kirilyuk.
This discovery paves the way to novel approaches in fundamental science. Ultrafast modification of the crystal field environment has the potential to become the most universal way to manipulate magnetization. It could be the starting point for innovative IT-concepts concepts such as ultrafast opto-spintronic devices.

Publication: A. Stupakiewicz, C.S. Davies, K. Szerenos, D. Afanasiev, K.S. Rabinovich, A.V. Boris,A. Caviglia, A.V. Kimel and A. Kirilyuk, Ultrafast phononic switching of magnetization, Nature Physics (2021)