1. Probing the in-plane electron spin polarization in Ge/ Si0.15Ge0.85 multiple quantum wells
- Author
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Michele Virgilio, Federico Bottegoni, Daniel Chrastina, Stefano Cecchi, Carlo Zucchetti, Andrea Ballabio, Marco Finazzi, and G. Isella
- Subjects
Physics ,Condensed matter physics ,Spin polarization ,Inverse ,Heterojunction ,02 engineering and technology ,Electron ,Photon energy ,021001 nanoscience & nanotechnology ,Polarization (waves) ,01 natural sciences ,Brillouin zone ,0103 physical sciences ,Condensed Matter::Strongly Correlated Electrons ,010306 general physics ,0210 nano-technology ,Spin (physics) - Abstract
We investigate spin transport in a set of $\text{Ge}/{\text{Si}}_{0.15}{\text{Ge}}_{0.85}$ multiple quantum wells (MQWs) as a function of the well thickness. We exploit optical orientation to photogenerate spin-polarized electrons in the discrete energy levels of the well conduction band at the $\mathrm{\ensuremath{\Gamma}}$ point of the Brillouin zone. After diffusion, we detect the optically oriented spins by means of the inverse spin-Hall effect (ISHE) taking place in a thin Pt layer grown on top of the heterostructure. The employed spin injection/detection scheme is sensitive to in-plane spin-polarized electrons, therefore, by detecting the ISHE signal as a function of the photon energy, we evaluate the spin polarization generated by optical transitions driven by the component of the light wave vector in the plane of the wells. In this way, we also gain insight into the electron spin-diffusion length in the MQWs. The sensitivity of the technique to in-plane spin-related properties is a powerful tool for the investigation of the in-plane component of the spin polarization in MQWs, which is otherwise commonly inaccessible.
- Published
- 2020