Regensburg 2016 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

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

MA 52.4: Hauptvortrag

Freitag, 11. März 2016, 11:15–11:45, H32

Spin transport and spin-orbit interaction at terahertz frequencies: spectroscopy and applications — •Tom Seifert — Fritz-Haber-Institute, Berlin, Germany

On the route toward spin-based electronics (spintronics), spin-orbit interaction (SOI) is envisioned to play a major role since it permits spin-to-charge conversion and vice versa via the spin Hall effect (SHE). To study the dynamics of the SHE and related effects, terahertz (THz) time-domain spectroscopy is a promising tool because THz photon energies (4 meV at 1 THz) are comparable with the energy scale of SOI (1-100 meV). At the same time, future spintronic devices should eventually operate at such elevated frequencies.
Here, we use two complementary approaches to address the interplay of SOI, electron and spin transport at THz frequencies. First, we employ broadband THz time-domain ellipsometry [A. Rubano et al., APL (2012)] to measure the anomalous Hall effect in various magnetic metals from 1 to 40 THz. Second, we use femtosecond laser pulses (800 nm, 10 fs, 2 nJ) to induce ultrafast spin currents in magnetic heterostructures which, through the inverse SHE, lead to emission of THz radiation [T. Kampfrath et al., NatNano (2013)]. Detection of the latter allows us to measure the spin current and the spin Hall angle in a contactless manner. Finally, optimization of these structures results in new, efficient, scalable and ultrabroadband emitters of THz electromagnetic pulses [T. Seifert et al., http://arxiv.org/abs/1510.03729 (2015)].