Abstract-Terahertz spectroscopy for all-optical spintronic characterization of the spin-Hall-effect metals Pt, W and Cu80Ir20

T. Seifert, N. M. Tran, O. Gueckstock, S. M. Rouzegar,
 L. Nadvornik, S. Jaiswal, G. Jakob. V. Temnov, M. Münzenberg,  M. Wolf,  M. Kläui, T. Kampfrath

https://arxiv.org/ftp/arxiv/papers/1805/1805.02193.pdf

 Identifying materials with an efficient spin-to-charge conversion is crucial for future spintronic applications. The spin Hall effect is a central mechanism as it allows for the interconversion of spin and charge currents. Spintronic material research aims at maximizing its efficiency, quantified by the spin Hall angle 𝛩 and the spin-current relaxation length 𝜆୰ୣ୪. We develop an all-optical method with large sample throughput that allows us to extract 𝛩 and 𝜆୰ୣ୪. and 𝜆୰ୣ୪. Employing terahertz spectroscopy, we characterize magnetic metallic heterostructures involving Pt, W and Cu80Ir20 in terms of their optical and spintronic properties. We furthermore find indications that the interface plays a minor role for the spin-current transmission. Our analytical model is validated by the good agreement with literature DC values. These findings establish terahertz emission spectroscopy as a reliable tool complementing the spintronics workbench.