Terahertz Emission Spectroscopy of SnSe Single Crystals

Sin-Yi Wei¹, Chen-Yu Chang¹, Min-Ru Kuo¹, Chia-Nung Kuo², Chien-Ming Tu^1*, Chin-Shan Lue², Chih-Wei Luo¹

¹Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
²Department of Physics, National Cheng Kung University, Tainan, Taiwan

* Presenter:Chien-Ming Tu, email:cmtu@nycu.edu.tw

Recently, spin-splitting of electronic bands has been demonstrated in monolayer SnSe by theoretical calculations with spin-orbit coupling, and a spin-polarized current can be generated by circularly polarized light excitation. In this study, we investigate the ultrafast carrier dynamics of bulk SnSe by terahertz emission spectroscopy. Using the decomposition-reconstruction procedure in the time domain, the contributions of circular photogalvanic effect can be extracted from the helicity-dependent THz emission with both 400 nm and 800 nm excitation. Meanwhile, the p- and s-polarized components of THz emission was also observed, which implies that the spin-splitting in electronic bands of bulk SnSe may originate from Rashba and Dresselhaus effects. We also measured the circular dichroism in THz emission at different azimuthal angles and found the in-plane anisotropy of spin poalrized currents in SnSe. These observations show that SnSe would be a potential candidate for the application of spintronics.

Keywords: terahertz emission, spin-polarized current, Rashba effect, Dresselhaus effect