First Principle Study of Nonlinear Optical Effects on 2D Ferromagnetic VSe₂

Li Wei Chang^1*, Guang Yu Guo^1,2

¹Physics, National Taiwan University, Taipei, Taiwan
²Physics, National Center for Theoretical Sciences, Taipei, Taiwan

* Presenter:Li Wei Chang, email:willy30406@gmail.com

2D Transition-metal dichalcogenides (TMDs) exhibit properties that are different from their bulk crystals. Recently, some experimental groups successfully synthesized a 2D type of TMDs, vanadium diselenide (VSe₂). VSe₂ is a ferromagnetic semiconductor in 2D 2H-phase, while it is a paramagnetic metal in bulk 1T-phase. Moreover, because of the inversion symmetry breaking, 2D VSe₂ with an odd layer number shows the nonlinear optical properties. In this work, we use first principle method to study the H-phase monolayer and trilayer VSe₂. We find large shift current and injection current in these 2D structures compared to other nonlinear optical materials. Also, we calculate the second harmonic generation and dielectric function. Our calculated nonlinear optical effects are in agreement with the available experimental results.

Keywords: 2D Transition-metal Dichalcogenides, VSe₂, Nonlinear Optical Effects, First Principle Calculation