Magneto-optical investigation of spin and carrier kinetics in Ge_1-xSn_x/Ge heterostructures

Germanium-tin alloys have sparked interest thanks to their ability to tailor electronic properties by strain and band-gap engineering and their compatibility with silicon technology. Exciting improvements in lasing performances and photodetection efficiencies in the strategic mid-infrared wavelength range have been recently enabled by out-of-equilibrium growth techniques¹.
Despite the outstanding properties of such novel alloys, their unique spin-dependent phenomena have remained completely unexplored. We specifically apply optical spin orientation combined with a magneto-optical analysis of the radiative emission to demonstrate coherent spin dynamics through quantum beat spectroscopy² and sub-ns carrier kinetics through the Hanle effect³.
Our results demonstrate that alloying can indeed offer a precise control of spin-orbit coupling in group IV semiconductors, thus opening exciting perspectives in emerging fields such as Rashba physics and spin Hall effect.
1) S. Wirths et al., Nat. Photonics, 9, 88 (2015)
2) S. De Cesari et al., Phys. Rev. B, 99, 035202 (2019).
3) E. Vitiello et al., arXiv:2009.01087