Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 92: Focus Session: Spinorbitronics - From Efficient Charge/Spin Conversion Based on Spin-Orbit Coupling to Chiral Magnetic Skyrmions II (joint session MA/TT)

TT 92.2: Vortrag

Donnerstag, 15. März 2018, 15:30–15:45, H 1012

Spin-charge interconversion in single crystalline Bismuth films grown on Ge(111) — •minh tuan dau¹, carlo Zucchetti², federico bottegoni², céline vergnaud¹, thomas guillet¹, alain marty¹, cyrille beigné¹, andrea picone², alberto calloni², giovanni isella², franco ciccacci², pranab kumar das³, jun fujii³, ivana vobornik³, marco finazzi², and matthieu jamet¹ — ¹INAC-Spintec, CEA/CNRS/Grenoble-INP and Université Grenoble Alpes, 38054 Grenoble, France — ²LNESS-Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy — ³CNR-IOM Laboratorio TASC, 34149 Trieste, Italy

In this study, we have grown a bismuth wedge (0-12 nm) on Ge(111) by molecular beam epitaxy. Using structural characterization (RHEED and x-ray diffraction), we found a critical thickness of ~ 4.5 nm below which Bi exhibits an allotropic pseudocubic phase. A careful angle-resolved and spin-resolved photoemission spectroscopy study using synchrotron radiation showed that the pseudocubic phase exhibits surface states with linear band dispersion and a characteristic helical spin texture. We have then investigated the spin-charge interconversion at these surface states using different techniques: magneto-optical Kerr effect to probe the spin Hall effect (SHE), inverse SHE using optical spin orientation in the Ge film beneath and finally spin pumping from a ferromagnetic layer grown on top of Bi separated by an Al spacer. We found a significant signature of the spin-charge interconversion in these surface states and a clear Bi-thickness dependence of the conversion signals.