Nonlinear Optical Spectroscopic Study of Topological Weyl Semimetals

Abstract

Topological Weyl semimetals demonstrate interesting properties like exotic surface fermi arcs and chiral Weyl points, making them a strong candidate for many potential applications in electronics, optoelectronics, and catalysis. However, currently, their identification requires demanding experimental conditions like low temperatures or ultrahigh vacuum. Hence, there is a need for experimental techniques that can identify their topological states under ambient conditions. Second-order nonlinear optical processes, being sensitive to breaks in symmetries, have the potential to identify topological states. We employed wavelength-dependent reflection SHG measurements to study the surface of thin films of Weyl semimetals Td-WTe2 and Mn3Sn. Our studies show some promising results such as the effect of wavelength and polarization geometry in understanding the surface electronic properties of these materials. The systems are also stable to continuous illumination and high power and repetition rates, and do not show any significant heating or charging effects within our experimental conditions.