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O: Fachverband Oberflächenphysik

O 94: 2D Materials and their Heterostructures II (joint session DS/HL/O)

O 94.1: Vortrag

Donnerstag, 19. März 2020, 09:30–09:45, CHE 89

Longitudinal Nonlinear Spin Sensitive Response in two-dimensional Materials — •Dominik Kreil, Mario Graml, and Helga M. Böhm — Institute of Theoretical Physics, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz, Austria

Future spin- and valleytronic devices will demand a deeper understanding of electronic systems. [1] With increasing intenstitys of state of the art terahertz lasers linear approximations become more imprecise. Nonlinear plasmonic effects arising from coherent oscillations of free charge carriers in metals or highly doped semiconductors serve to enhance optical processes. The underlying dynamics of electrons (or holes) was successfully treated semi-classically [2] 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 as in Ref. [3] we also derive a closed formula for longitudinal nonlinear spin sensitive response functions 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 electron gas with parabolic dispersion and in graphene [4,5] is presented.
References: [1] Vitale et al., Small 14, 1801483 (2018). [2] Krasavinet al., Laser & Photonics Reviews 12, 1700082 (2018). [3] Mikhailov, Phys. Rev. B. 93, 085403 (2016). [4] D. Kreil et al., Phys. Rev. B. 92, 085403 (2015). [5] D. Kreil et al., Lithuanian J. Phys. 59, 35 (2019).