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

Tom Seifert, Ngoc Minh Tranh, Oliver Gueckstock, Seyed Mohammedreza Rouzegar, Lukas Nadvornik,  Samridh Jaiswal, Gerhard Jakob, Vasily Temnov, Markus Muenzenberg,

http://iopscience.iop.org/article/10.1088/1361-6463/aad536

Identifying materials with an efficient spin-to-charge conversion is crucial for future spintronic applications. In this respect, 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 <i>Θ</i><sub>SH</sub> and the spin-current relaxation length <i>λ</i><sub>rel</sub>. We develop an all-optical contact-free method with large sample throughput that allows us to extract <i>Θ</i><sub>SH</sub> and <i>λ</i><sub>rel</sub>. Employing terahertz spectroscopy and an analytical model, magnetic metallic heterostructures involving Pt, W and Cu<sub>80</sub>Ir<sub>20</sub> are characterized in terms of their optical and spintronic properties. The validity of our analytical model is confirmed by the good agreement with literature DC values. For the samples considered here, we find indications that the interface plays a minor role for the spin-current transmission. Our findings establish terahertz emission spectroscopy as a reliable tool complementing the spintronics workbench.