Regensburg 2013 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 33: Magnetization Dynamics I of 3

MA 33.10: Vortrag

Donnerstag, 14. März 2013, 11:45–12:00, H22

Optically induced ultrafast spin dynamics in Au/Fe/MgO(001) structures: the role of hot carrier transport — •Alexandr Alekhin¹, Damian Bürstel², Tim O. Wehling³, Detlef Diesing², Alexander I. Lichtenstein⁴, Uwe Bovensiepen⁵, and Alexey Melnikov¹ — ¹Fritz-Haber-Institut der MPG, Dep. of Phys. Chem., Berlin, Germany — ²University of Duisburg-Essen, Insitute of Phys. Chem., Essen, Germany — ³University of Bremen, Institute of Theor. Phys., Bremen, Germany — ⁴University of Hamburg, Institute of Theor. Phys., Hamburg, Germany — ⁵University of Duisburg-Essen, Dep. of Physics, Essen, Germany

Spin dynamics (SD) induced by ultrashort laser pulses is of great importance in light of recent advance in spintronics and attempts to control magnetization on femtosecond (fs) time scales. To understand the origin of ultrafast demagnetization, pump-probe experiments have been performed on epitaxial Au/Fe/MgO(001) structures. Using 14 fs laser pulses to probe the Fe side of the samples, we monitor bulk SD by the magneto-optical Kerr effect (MOKE) and SD at interfaces by the magneto-induced second harmonic generation (mSHG). To disentangle interfering mSHG contributions from different interfaces, we have analyzed the dependence of mSHG response on the thickness of Fe film. This approach gives us an access to spatially non-uniform transient magnetization. Comparison of transient mSHG response of Fe to direct optical excitation with that to excitation by hot carriers (HC) generated in Au reveals a significant contribution of spin polarized HC transport to ultrafast demagnetization.