Optical valleytronics of impurity states in two-dimensional Dirac materials

Abstract

We analyze the valley selection rules for optical transitions from impurity states to the conduction band in two-dimensional Dirac materials, taking a monolayer of MoS2 as an example. We employ the analytical model of a shallow impurity potential which localizes electrons described by a spinor wave function, and, first, find the system eigenstates taking into account the presence of two valleys in the Brillouin zone. Then, we find the spectrum of the absorbance and calculate the photon-drag electric current due to the impurity-band transitions, drawing the general conclusions regarding the valley optical selection rules for the impurity-band optical transitions in gapped Dirac materials.

Bogolon-mediated light absorption in atomic condensates of different dimensionality

“…This phenomenon is often referred to as the photon drag effect. It has been widely studied in generic two-dimensional (2D) electron gas and graphene systems 1 , 2 , metal films 3 , 4 , topological insulators 5 , 6 , van der Waals structures and Dirac materials 7 , 8 , and cavities 9 .…”

Impurity-band optical transitions in two-dimensional Dirac materials under strain-induced synthetic magnetic field

“…The theoretical description of the properties of optical transitions from bands to impurity states and back and the analysis of the optical characteristics of these transitions (which depend on the valley quantum number) is an important problem in valleyoptoelectronics of two-dimensional semiconductors. In particular, the selection rules here can be different from the interband transitions since one deals with a set of discrete states, characterized by the radial and angular momentum quantum numbers [22], whereas the translational momentum represents a bad quantum number due to the localization of electrons on impurities.…”