Regensburg 2000 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 17: Postersitzung II: Pinning und Vortexdynamik (1-8), Supraleitung: Theorie (9-13), Korrelierte Elektronen (14-48), Niederdimensionale Systeme (49-68), Quantenflüssigkeiten (69-75)

TT 17.22: Poster

Mittwoch, 29. März 2000, 14:30–18:00, A

Origin of the Charge-Orbital Stripe Structure in La_1−xCa_xMnO₃ (x=1/2, 2/3) — •Hiroshi kontani^1,2 and Tetsuya Mutou³ — ¹Theoretische Physik III, Universität Augsburg, 86135 Augsburg — ²ISSP, University of Tokyo, Japan — ³Inst. of Physical and Chemical Research (RIKEN), Japan

We propose the origin of the charge-ordered stripe structure with the orbital ordering observed experimentally in La_1−xCa_xMnO₃ (x=1/2, 2/3), in which the long-range Coulomb interaction plays an essential role. We study a Hubbard model with doubly-degenerate e_g orbitals, and treat the on-site Coulomb interaction (U) and the nearest-neighbor one (V) with the Hartree-Fock approximation. Both the charge and orbital ordering structures observed in experiments are reproduced in a wide region of the U-V phase diagram determined by the present study. The stability of the orbital ordering is also confirmed by the perturbation theory.