Light-Induced Metastable Hidden Skyrmion Phase in the Mott Insulator Cu 2 OSeO 3 .

The article reports the discovery of a novel long-lived metastable skyrmion phase in the multiferroic insulator Cu 2 OSeO 3 visualized with Lorentz transmission electron microscopy for magnetic fields below the equilibrium skyrmion pocket. This phase can be accessed by exciting the sample non-adiabatically with near-infrared (NIR) femtosecond laser pulses and can not 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. This effect results in a transient modification of the magnetic free energy landscape extending the equilibrium skyrmion pocket to lower magnetic fields. We monitored the evolution of the photoinduced phase for over 15 minutes and found no decay. Because such a time is much longer than the duration of any transient effect induced by a laser pulse in a material, we assume that the new skyrmion state we discovered is stable for practical purposes, thus breaking ground for a novel approach to control magnetic state on demand at ultrafast timescales and drastically reducing heat dissipation relevant for next generation spintronic devices. This article is protected by copyright. All rights reserved.