[3Ga01-10] Surface Science(SS1) Physical Property

[3Ga08] Helicity-dependent photocurrent induced by circularly polarized infrared light at atomic bilayer superstructure Si(111)-√3×√3-(Tl, Sn)

*Ibuki Taniuchi¹, Ryota Akiyama¹, Rei Hobara¹, Shuji Hasegawa¹ (1. Department of Physics, The University of Tokyo)

In materials having strong spin-orbit interaction (SOI) with spin-splitting bands, asymmetric electron excitation occurs due to the spin-selective excitations by circularly polarized light (CPL). Such excited carriers form helicity-dependent photocurrent (HDP). Pure spin current can be induced under some conditions, which can be detected electrically by inverse spin Hall effect. We observed HDP induced by infrared CPL laser (λ = 1550 nm) at the sample edges of bilayer superstructure, Si(111)-√3×√3-(Tl, Sn), which has giant Rashba effect. HDP increased with the laser spot going to both edges of the sample and the sign of HDP reversed between the two edges. Contrary to the behavior reported so far, HDP became larger when CPL was irradiated more obliquely, that is, the in-plane component of the injected spin increased. Here, we have successfully explained such behaviors as a superposition phenomenon by Inverse Spin Hall Effect and the precession of electrons’ spin due to the strong SOI.