Ricardo I. Gomez-Abal

Localized and itinerant states in lanthanide oxides united by GW @ LDA + U

Many-body perturbation theory in the GW approach is applied to lanthanide oxides, using the local-density approximation plus a Hubbard U correction (LDA+U) as the starting point. Good agreement between the G0W0 density of states and experimental spectra is observed for CeO2 and Ce2O3. Unlike the LDA+U method G0W0 exhibits only a weak dependence on U in a physically meaningful range of U values. For the whole lanthanide sesquioxide (Ln2O3) series G0W0 @ LDA+U reproduces the main features found for the optical experimental band gaps. The relative positions of the occupied and unoccupied f states predicted by G0W0 confirm the experimental conjecture derived from phenomenological arguments.

The role of spin–orbit coupling in optically induced ultrafast magnetic dynamics

Spin–orbit coupling (SOC) plays a major role in solid-state magnetism. Its effects range from completely defining the splitting of f states in rare earths to the correct prediction of the ground-state orientation of the magnetic moment in transition metals. The breaking of symmetries that it produces is the main tool for addressing magneto-optical effects. In this paper we theoretically study the possibility of all-optical spin switching. By simulating the effect of an ultrashort laser pulse on an electronic system, we show the crucial role of SOC in the spin dynamics occurring in this regime. The role of other parameters is also analysed. Finally, we show the possibility of obtaining an all-optical spin switching in the subpicosecond time regime.