We investigate the effect of the oft-neglected cubic terms of the Dresselhaus spin-orbit coupling on the longitudinal current response of a two-dimensional electron gas with both Rashba and linear Dresselhaus interactions. Changes caused by these nonlinear-in-momentum terms on the absorption spectrum becomes more notable under SU(2) symmetry conditions, when the Rashba and linear Dresselhaus coupling strengths are tuned to be equal. The longitudinal optical response no longer vanishes then and shows a strong dependence on the direction of the externally applied electric field, giving a signature of the relative size of the several spin-orbits contributions. This anisotropic response arises from the non isotropic splitting of the spin states induced by the interplay of Rashba and Dresselhaus couplings. However, the presence of the cubic terms introduces characteristic spectral features and can modify the overall shape of the spectra for some values of the relative sizes of the spin-orbit parameters. In addition to the control through the driven frequency or electrical gating, this directional aspect of the current response suggests new ways of manipulation and supports the use of interband optics as a sensitive probe of spin-orbit mechanisms in semiconductor spintronics.
We investigate the dielectric response, the optical conductivity, and the plasmon spectrum of a two-dimensional electron gas with Rashba and Dresselhaus spin–orbit (SO) interaction. Using the self-consistent field approach, we derive expressions for the dispersion relations of the intra- and inter-SO plasmons. We found that the latter is immersed within the continuum of inter-SO single-particle excitations. The intra-SO plasmons remain undamped and almost unaffected by the SO coupling. The longitudinal optical conductivity shows, however, a dependence on the direction of the externally applied potential, caused by the anisotropic splitting of the spin states. In addition to the control through the driving frequency or electrical gating, this new aspect of the optical absorption spectrum might be useful in spintronics applications.
We investigate the optical conductivity and plasmon spectrum of a two-dimensional electron gas with Rashba and
Dresselhaus spin-orbit interaction. Using the self-consistent field approach we derive expressions for the dispersion
relations of the intra- and inter-SO plasmons. We found that the latter are immersed within the continuum of
inter-SO single-particle excitations. The intra-SO plasmons remain undamped and almost unaffected by the
spin-orbit coupling. Remarkably, the optical conductivity shows however a dependence on the direction of the
externally applied electric field, caused by the anisotropic splitting of the spin states. In addition to the control
through the driving frequency or electrical gating, this new aspect of the optical absorption spectrum might be
useful in spintronics applications.
KEYWORDS: Near field scanning optical microscopy, Near field optics, Near field, Microscopes, Polarization, Nonlinear optics, Second-harmonic generation, 3D image processing, Image resolution, Scanning tunneling microscopy
Existing optical scanning microscopes don't allow the determination of the depth below the surface of the sample under which where scatterers might be located, due to the simple exponential decay of their evanescent probing field. We propose a nonlinear near field microscope which would allow three dimensional images of buried structures with nanometric resolution along all dimensions.
A harmonic oscillator may display a nonlinear behavior when forced by an inhomogeneous field. We calculate the response of harmonic molecules adsorbed on a surface to a monochromatic electric field employing algebraic methods. The field inhomogeneity, due to image effects, produces harmonics which we evaluate non-perturbatively as a function of the intensity and frequency of the field and the distance to the substrate. We compare the results with those obtained using perturbation theory.
The bulk electric-dipole contribution to the optical second harmonic generation (SHG) of centrosymmetric systems is (almost) null, so that SHG constitutes a good optical probe of their surface. We present a generalized hydrodynamic model for the calculation of the SHG spectra of simple metals with a smoothly varying surface electronic density profile. The equations of motion include a pressure term derived from the Thomas-Fermi-Dirac-von Weizsacker energy-functional, thus it includes some effects of exchange and correlation. The surface is capable of sustaining multipolar collective modes besides the ordinary surface plasmon. The former have proved capable of sustaining multipolar collective modes besides the ordinary surface plasmon. The former have proved to be very elusive and have only recently been observed with HREELS. We have obtained very large peaks in the non-linear susceptibility at the frequency of the multipolar resonance and its subharmonic, at which the SHG efficiency is enhanced several orders of magnitude, suggesting the usefulness of SHG as a probe of surface collective modes.
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