Regensburg 2016 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 52: Focus: Ultrafast spin currents for spin-orbitronics: from metals to topological insulators

MA 52.1: Hauptvortrag

Freitag, 11. März 2016, 09:30–10:00, H32

Experimental separation of various mechanisms leading to laser-pulse-induced magnetization precession in (Ga,Mn)As — •Petr Nemec — Charles University in Prague, Ke Karlovu 3, 121 16 Prague 2, Czech Republic

Ferromagnetic semiconductor (Ga,Mn)As is a favorable material for observing optical spin torques because the direct-gap GaAs host allows the generation of high density non-equilibrium photo-carriers and the carrier spins interact with ferromagnetic moments on Mn via strong exchange coupling [1]. In this contribution we show how various excitation mechanisms leading to laser-pulse-induced magnetization precession in (Ga,Mn)As can be experimentally separated. In particular, we demonstrate how the optical spin transfer torque, which is a non-relativistic phenomenon where angular momentum of spin polarized electrons photoinjected by circularly polarized laser pulse is transferred to the magnetization [2], and optical spin-orbit torque, which is a relativistic phenomenon originating from spin-orbit coupling of non-equilibrium photocarriers [3], can be separated from each other and from the thermal mechanism. We also illustrate how the laser-induced magnetization dynamics can be used for a determination of magnetic parameters of (Ga,Mn)As [4] and other materials.

[1] T. Jungwirth et al., Rev. Mod. Phys. 86, 855 (2014). [2] P. Nemec et al., Nature Physics 8, 411 (2012). [3] N. Tesarova et al., Nature Photonics 7, 492 (2013). [4] P. Nemec et al., Nature Communications 4:1422 (2013).