Driving magnetic order in a manganite by ultrafast lattice excitation

Abstract

Femtosecond midinfrared pulses are used to directly excite the lattice of the single-layer manganite La${}_{0.5}$Sr${}_{1.5}$MnO${}_{4}$. Magnetic and orbital orders, as measured by femtosecond resonant soft x-ray diffraction with an x-ray free-electron laser, are reduced within a few picoseconds. This effect is interpreted as a displacive exchange quench, a prompt shift in the equilibrium value of the magnetic- and orbital-order parameters after the lattice has been distorted. Control of magnetism through ultrafast lattice excitation may be of use for high-speed optomagnetism.