Ultrafast magnetization dynamics in diluted magnetic semiconductors

Omar Morandi (1, 2) , Paul-Antoine Hervieux (1) , Giovanni Manfredi (1)

1 IPCMS - Institut de Physique et Chimie des Matériaux de Strasbourg
2 CALVI - Scientific computation and visualization

We present a dynamical model that successfully explains the observed time evolution of the magnetization in diluted magnetic semiconductor quantum wells after weak laser excitation. Based on the pseudo-fermion formalism and a second-order many-particle expansion of the exact p-d exchange interaction, our approach goes beyond the usual mean-field approximation. It includes both the sub-picosecond demagnetization dynamics and the slower relaxation processes that restore the initial ferromagnetic order in a nanosecond timescale. In agreement with experimental results, our numerical simulations show that, depending on the value of the initial lattice temperature, a subsequent enhancement of the total magnetization may be observed within the timescale of a few hundred picoseconds.

Mots clés: diluted magnetic semiconductor quantum wells; ultrafast demagnetization

Domaines: Physique Quantique [quant-ph]; Science des matériaux [cond-mat.mtrl-sci]; Autre [cond-mat.other]

Omar Morandi, Paul-Antoine Hervieux, Giovanni Manfredi. Ultrafast magnetization dynamics in diluted magnetic semiconductors. New Journal of Physics, 2009, 11, pp.073010. ⟨10.1088/1367-2630/11/7/073010⟩. ⟨hal-00596704⟩