Regensburg 1998 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 21: Postersitzung III: Spin-Peierls-Systeme, Metall-Isolator-Übergang, Lokalisierung; SL: Theorie; Quantenflüssigkeiten und -kristalle; Amorphe Materialien, Tunnelsysteme; Borcarbide, Fullerene, konventionelle SL; SL dünner Filme; Experimentiertechniken

TT 21.16: Poster

Donnerstag, 26. März 1998, 15:00–18:30, D

Energy Level Statistics and Localization for Two Interacting Particles in a Random Potential — •O. Halfpap, I. Zharekeshev, and B. Kramer — I. Institut für Theoretische Physik, Jungiusstraße 9, D-20355 Hamburg

The energy spectrum and the localization properties of two strongly correlated electrons are investigated in a one-dimensional disordered system. The density of states calculated by an exact diagonalization is similar to that of a single electron in two dimensions. Near the center of the band, the level statistics show a crossover between Poissonian and Wigner distribution in dependence on the interaction strength, indicating the interaction induced coupling of the non-interacting basis states, in agreement with [1]. The localization length is calculated within the bag model by using the transfer matrix method. For a Hamiltonian discretized in center of mass and relative coordinates we find an enhancement of the localization length even for vanishing interaction strength as in [2](Hamiltonian discretized in particle coordinates). By performing a finite-size scaling analysis we obtain a much stronger enhancement. Switching on the interaction does not change this behavior substantially.

[1] D. Weinmann und J.-L. Pichard, Phys. Rev. Lett. 77, 1556 (1996)

[2] K. Frahm et al, Europhys. Lett. 31, 169 (1995)

[3] O. Halfpap, I. Zharekeshev und B. Kramer preprint