Dresden 2017 – scientific programme
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MA: Fachverband Magnetismus
MA 47: Spin Hall Effects and Skyrmions I
MA 47.11: Talk
Thursday, March 23, 2017, 12:15–12:30, HSZ 04
Optimizing the spin Hall angle above 100% — •Christian Herschbach1, Dmitry Fedorov2,1, Martin Gradhand3, and Ingrid Mertig1,2 — 1Martin Luther University Halle-Wittenberg, Halle, Germany — 2Max Planck Institute of Microstructure Physics, Halle, Germany — 3University of Bristol, Bristol, United Kingdom
The spin Hall effect (SHE) is one of the key effects in modern spintronics creating pure spin currents directly in nonmagnetic materials. The effect’s strength is usually quantified with the so-called spin Hall angle (SHA), which is the ratio of the transverse spin conductivity to the longitudinal charge conductivity. Reported values based on both experimental and theoretical investigations increased during the last years. Measurements on Pt-doped Au samples yielded a SHA of about 10% introduced as giant SHE [1] while a SHA of 24% was published for thin-film Cu(Bi) alloys [2]. The large effect caused by Bi impurities in Cu was theoretically predicted for bulk samples [4]. Further theoretical investigations on Bi-doped ultrathin noble-metal films forecast colossal SHAs slightly below 100% [5].
In this work we further investigate the possibility to optimize the SHE. We identify systems with a strong anisotropy of the in-plane transport properties that lead to SHAs above 100%.
[1] Seki et al., Nat. Mater. 7, 125 (2008)
[2] Niimi et al., Phys. Rev. Lett. 109, 156602 (2012)
[3] Pai et al., Appl. Phys. Lett. 101, 122404 (2012)
[4] Gradhand et al., Phys. Rev. Lett. 104, 186403 (2010)
[5] Herschbach et al., Phys. Rev. B 90, 180406(R) (2014)