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MA: Fachverband Magnetismus

MA 23: Spin Dynamics and Transport: Ultrafast Effect

MA 23.2: Vortrag

Dienstag, 21. März 2017, 09:45–10:00, HSZ 403

Ultrafast magnetization dynamics triggered by intense terahertz pulses — •Julius Heitz, Tom Seifert, and Tobias Kampfrath — Fritz-Haber-Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany

We excite ferromagnetic iron thin films with sub-picosecond terahertz (THz) pulses covering the spectrum from 0.5 to 2 THz. Measurement of the magnetooptical Kerr effect (MOKE) by optical probe pulses (duration of 10 fs, center wavelength 800 nm) provides access to the time evolution of the sample magnetization. The different contributions to the magnetization dynamics are disentangled by comparing measurements with opposite THz field polarities and with different equilibrium sample magnetization. In particular, we discuss the contributions of ultrafast demagnetization and THz Zeeman torque.

The results shown here were obtained in close collaboration with the research groups of E. Beaurepaire , M. Kläui and M. Münzenberg.