Electromagnetic scattering by gyrotropic semiconductor spheres when considering spatial dispersion

A new solution is presented to analyze the electromagnetic response of an anisotropic sphere when both the spatial dispersion and gyrotropy are simultaneously accounted for. By employing the Mie theory, the electromagnetic fields that can be decomposed into source-free and curl-free vector spherical harmonics are derived analytically by applying appropriate boundary conditions, namely, the continuity of the tangential components of electric fields and magnetic fields, respectively, together with the continuity of the normal components of the polarization phasor current density. Moreover, all expressions involving gyrotropic tensors are calculated in the corresponding principle coordinates, yielding analytical expressions. The derived solutions are capable of dealing with incident electromagnetic waves at an arbitrary incident angle and for arbitrary polarizations. Numerical validations are performed by comparing our results with those obtained for simplified models and also with numerical solutions, as well as with the results obtained from other existing approaches. The impact of the temperature and the dispersion effects on the modified circular dichroism has been investigated. It is demonstrated that the interplay of spatial dispersion and gyrotropy can bring narrower relative frequency shifts between the magneto-plasmonic resonances of the left-circularly-polarized and the right-circularly-polarized wave excitations, along with a blue-shift of the resonance and the reduced magnitude of the spectrum. The proposed method shows its capability and flexibility to analyze the nonlocal response of gyrotropic plasmonic semiconductors under an external static magnetic field, which enables us to rapidly validate nonlocal magneto-plasmonic applications.