Nonlinear Charge- and Spin-Response to Longitudinal Fields
Sprache des Vortragstitels:
Mauterndorf Winterschool 2020
Sprache des Tagungstitel:
Nonlinear plasmonic effects arising from coherent oscillations of free charge carriers in metals or highly doped semiconductors serve to enhance optical processes in nanoelectronics. The underlying dynamics of electrons (or holes) was successfully treated semi-classically in three-dimensional (3D) nanostructures; quantum expressions for up to the third order of the longitudinal nonlinear polarizabilities of the 3D, 2D and 1D homogeneous electron
gases as well as graphene are also known. We here present a general discussion of higher order response functions resulting from
time-dependent perturbation theory. Using the random phase approximation, we also derive a closed formula for the longitudinal nonlinear response in arbitrary order. It holds for all the above listed systems and for imbalanced spin- or valley-polarizations. An application to the 2D
spin-polarized egas with parabolic dispersion and in graphene is presented.