Nonthermal magnetization pathways in photoexcited semiconductors

Abstract

The stabilization of long-range magnetic order in nominally non-magnetic semi-conductors using femtosecond light pulses is an exciting yet experimentally challenging goal. Theoretical studies indicate that certain non-magnetic semi-conductors can exhibit transient magnetic instabilities following above-gap laser excitation, but the dynamical pathways leading to these states remain largely unexplored. In this work, I introduce a minimal real-time spin-orbital model and identify the fundamental microscopic mechanisms that enable the emergence of a transient magnetic order. I then discuss the relevance of these findings for real materials employing a phenomenological time-dependent Ginzburg-Landau model. Finally, I analyze the strengths and limitations of current first-principles methodologies for investigating dynamically induced broken-symmetry states in the light of the present results.