Ultrafast control of magnetic interactions via light-driven phonons*

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 show that light-driven lattice vibrations can be utilized to coherently manipulate macroscopic magnetic states. We demonstrate that mid-infrared electric field pulses, tuned in resonance with a vibrational mode of the prototypical antiferromagnetic DyFeO₃, can induce ultrafast and long-living changes of the fundamental exchange interaction between rare-earth orbitals and transition metal spins. As the magnetic exchange defines the stability of the macroscopic magnetic state, this provides control over the magnetic phases. For sufficiently strong excitation, we demonstrate a coherent switching between competing antiferromagnetic and weakly ferromagnetic spin orders on the picosecond timescale.


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