Light-Induced Metastable Hidden Skyrmion Phase in the Mott Insulator Cu OSeO.

The discovery of a novel long-lived metastable skyrmion phase in the multiferroic insulator Cu OSeO visualized with Lorentz transmission electron microscopy for magnetic fields below the equilibrium skyrmion pocket is reported. This phase can be accessed by exciting the sample non-adiabatically with near-infrared femtosecond laser pulses and cannot be reached by any conventional field-cooling protocol, referred as a hidden phase. From the strong wavelength dependence of the photocreation process and via spin-dynamics simulations, the magnetoelastic effect is identified as the most likely photocreation mechanism.