Berlin 2012 – wissenschaftliches Programm
MA 18.2: Vortrag
Dienstag, 27. März 2012, 09:45–10:00, H 0112
Ultrafast Enhancement of Ferromagnetism via Photoexcited Carriers in EuO — •Masakazu Matsubara1, Andreas Schmehl2, Jochen Mannhart3, Darrell G. Schlom4, Mauricio Trujillo Martinez5, Johann Kroha5, and Manfred Fiebig1 — 1Department of Materials, ETH Zürich, Switzerland — 2Institut für Physik, Universität Augsburg, Germany — 3Max Planck Institute for Solid State Research, Germany — 4Department of Materials Science and Engineering, Cornell University, USA — 5Physikalisches Institut, Universität Bonn, Germany
EuO is a magnetic semiconductor, which undergoes a ferromagnetic transition at the Curie temperature (TC) of 69 K. Electron doping to the stoichiometric compound greatly enhances the TC and is accompanied by a nearly 100% spin polarization of the charge carriers in the ferromagnetic state, which makes electron-doped EuO a very attractive candidate for spintronics applications.
Here we have explored the possibility of the ultrafast control of magnetic properties of EuO via photoexcited carriers by a femtosecond pulse laser irradiation. Ultrafast spin dynamics was investigated in a variety of Gd-doped EuO (Eu1−xGdxO) films with different carrier densities and TC, exploiting the time-resolved magnetization-induced second-harmonic generation. The results show the ultrafast increase of magnetization, with a characteristic temperature dependence, in low/medium Gd-doped samples. This is attributed to the increase of the indirect exchange interaction mediated by the photoexcited carriers.