Nonlinear Circular Photogalvanic Effect in WSe₂

Circular photogalvanic effect (CPGE) is known to occur in systems where the spin direction of the carriers is coupled to the momentum, i.e. in systems with spin momentum locking. The effect has been observed in semiconductor heterostructures[1], topological insulators[2], van der Waals materials [3] and Dirac semimetals[4]. It is generally understood that CPGE emerges only when the inversion symmetry is broken. Here we study CPGE in WSe2 nanoflakes, which possess structure inversion symmetry. The thickness of the flakes were a few tens of nanometers. A laser light with a wave length in the infrared was applied. We find helicity dependent photocurrent that increases with increasing laser power. The power dependence of the helicity dependent photocurrent will be discussed in the presentation.



[1] Ivchenko and Ganichev, arXiv:1710.09223. [2] Plank et al. Phys. Rev. Mater. 2, 024202 (2018). [3] Yuan, H. et al. Nature Nanotech 9, 851–857 (2014). [4] Hirose et al. Appl. Phys. Lett. 113, 222404 (2018).