Fig. 1: Giant THz-frequency nonlinearities in 1 T’ MoSSe.
From: Giant room-temperature nonlinearities in a monolayer Janus topological semiconductor
a Schematic illustration of THz emission spectroscopy (TES), mid-infrared high-harmonic generation (HHG), and near-infrared second harmonic generation (SHG) in 1 T’ MoSSe. b The lattice structure of 1 T’ MoSSe, 1 T’ MoS2, 2H MoSSe, 2H MoS2. c Schematic illustration of the topological band inversion in the 1 T’ phase (left) compared with the topologically trivial band structure of the 2H phase. The colormap (red and blue) indicates the wavefunction contributions from contributed by different atomic electron orbitals (e.g., chalcogen p and metal d orbitals.), and the 1 T’ phase exhibits a hybridization between the original valence and the conduction bands. d Optical images of 1 T’ MoSSe (top) and 2H MoSSe (bottom). e Experimental and theoretical Raman spectrum of 1 T’ MoSSe and experimental Raman spectrum of 2H MoSSe.
