Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 65: Poster 2

MA 65.23: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-OG1

Probing the Spin Hall Effect of β-Tungsten by Terahertz Emission Spectroscopy — •Oliver Gückstock¹, Tom Seifert¹, Sebastian Dapper², Satya Prakash Bommanaboyena², Markus Meinert², and Tobias Kampfrath¹ — ¹Fritz Haber Institut, MPG, Berlin, Deutschland — ²Universität Bielefeld, Bielefeld, Deutschland

The efficient conversion of spin into charge currents driven by spin-orbit interaction (SOI) will be highly important for future spin-based electronics [1]. Recently, much effort has been devoted to the identification of new large-SOI materials. One promising material is β-tungsten, for which large spin Hall angles (SHA) have been reported [2]. However, it remains unclear to which extent such a large SHA is caused by an increased SOI or by a decreased longitudinal conductivity. In our experiments, we employ femtosecond optical pulses to trigger ultrafast spin transport in magnetic thin-film stacks. Due to SOI, this spin current is partially converted into a transverse charge current which is monitored by detecting the concomitantly emitted THz electromagnetic radiation [3,4]. In particular, we study THz emission from bilayers of ferromagnetic cobalt-iron-boron and nonmagnetic β-tungsten with varying oxygen concentration. By additionally measuring the THz conductivity of these films, we are able to separate the influence of the spin-Hall conductivity and the longitudinal conductivity to the SHA.

References: [1] S.A. Wolf et al., Science 294.5546 (2001), [2] K. Demasius et al., Nature Comm. 7, 10644 (2016), [3] T. Kampfrath et al., Nature Nanotech. 8, 256 (2013), [4] T. Seifert et al., Nature Phot. 10, 483 (2016)