Light-driven ultrafast phonomagnetism*

Over the past few decades, ultrashort pulses of light have been widely employed to control the behavior of matter in its different phases. This is a particularly interesting challenge in magnetism, where the speed, dissipation and routes for ultimately fast switching of the spin orientation often lead to proposals for novel approaches in information processing and data recording. ^[1]
In this work we control the magnetic state by resonantly pumping optical phonons, low-energy elementary vibrations of the crystalline lattice. We demonstrate that by exciting the crystal lattice of the prototypical antiferromagnetic DyFeO₃, it can be driven within picoseconds into a transient metastable magnetic state. The state is characterized by a change in the strength of magnetic anisotropy along different crystal axes. This is experimentally seen as a long-lived shift in the frequency of the spin precession driven along the corresponding axes. For sufficiently strong excitation, this promotes an instability of the initial magnetic structure and launches a spin reorientation transition within a few picoseconds.

[1] P. Němec et al., Nature Physics 14, 229 (2018).