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HL: Halbleiterphysik
HL 9: Quantendr
ähte
HL 9.5: Vortrag
Montag, 27. März 2000, 17:30–17:45, H15
Self-consistent nonlinear RPA screening of strong Coulomb scatterer by one-dimensional electron gas — •P. Vagner1,2, M. Moško2, and Th. Sch"apers1 — 1Institut für Schicht- und Ionentechnik, Forschungszentrum Jülich GmbH, 52425 Jülich — 2Institute of Electrical Engineering, Slovak Academy of Sciences, 842 39 Bratislava, Slovakia
We investigate the screening of a Coulomb impurity by a one-dimensional (1D) electron gas confined in the ground-energy subband of a GaAs quantum wire. The impurity potential perturbs the wave functions of the 1D electrons and thus induces the polarization responsible for screening. In the random phase approximation (RPA) the polarization potential is given by the Hartree many-electron potential and the RPA screening comes out analytically as Lindhard dielectric function, if the Hartree problem is linearized by assuming that the perturbation acts on the electron wave functions as a weak Born scatterer. In this work we abandon the Born approximation, solve the problem exactly (numerically) as a self-consistent nonlinear Hatree problem, and demonstrate the breakdown of the linear RPA screening for an impurity positioned inside the quantum wire. In particular, the exact dielectric function can be order(s) of magnitude smaller than the Lindhard function and does not exhibit the logarithmic 2kF divergence typical for the Lindhard function of the 1D system at 0 K. Similarly, the resulting impurity potentials also strongly differ and their scattering cross sections (reflection coefficients) differ as well.