Controllable nonreciprocal optical response and handedness-switching in magnetized spin orbit coupled graphene

TL;DR

This paper theoretically investigates the optical properties of magnetized graphene with Rashba SOC, revealing controllable nonreciprocal responses and handedness-switching effects useful for polarization control.

Contribution

It provides a detailed theoretical analysis of the dynamical optical conductivity and permittivity tensor in magnetized spin orbit coupled graphene, highlighting controllable handedness-switching phenomena.

Findings

Identification of two well-separated peaks in optical response for intermediate magnetization

Calculation of frequency-dependent permittivity tensor across various parameters

Demonstration of handedness-switching controlled by chemical potential and magnetization

Abstract

Starting from a low-energy effective Hamiltonian model, we theoretically calculate the dynamical optical conductivity and permittivity tensor of a magnetized graphene layer with Rashba spin orbit coupling (SOC). Our results reveal a transverse Hall conductivity correlated with the usual nonreciprocal longitudinal conductivity. Further analysis illustrates that for intermediate magnetization strengths, the relative magnitudes of the magnetization and SOC can be identified experimentally by two well-separated peaks in the dynamical optical response (both the longitudinal and transverse components) as a function of photon frequency. Moreover, the frequency dependent permittivity tensor is obtained for a wide range of chemical potentials and magnetization strengths. Employing experimentally realistic parameter values, we calculate the circular dichroism of a representative device consisting of magnetized spin orbit coupled graphene and a dielectric insulator layer, backed by a metallic plate. The results reveal that this device has different relative absorptivities for right-handed and left-handed circularly polarized electromagnetic waves. It is found that the magnetized spin orbit coupled graphene supports strong handedness-switchings, effectively controlled by varying the chemical potential and magnetization strength with respect to the SOC strength.