Hamburg 2001 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 6: Postersitzung I: Josephsonkontakte und SQUIDs, Supraleitung: Theorie, Korrelierte Elektronen, Niederdimensionale Systeme, Magnetotransport, Quantenhalleffekt, Kohlenstoff-Nanoröhrchen, Quantenflüssigkeiten

TT 6.18: Poster

Montag, 26. März 2001, 14:30–17:00, Rang S\ 3

Numerical simulations of the Hubbard-Kondo model. — •M. Feldbacher and F. F. Assaad — Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart

We consider the half-filled two-dimensional Kondo lattice model with hopping t, exchange J and additional Hubbard repulsion U on the conduction electrons. At U =0 the competition between the RKKY interaction and Kondo effect triggers a quantum phase transition as a function of J/t between magnetically ordered and disordered insulators [1,2]. It is shown that increasing U reduces the critical value of J/t. Spin and charge dynamics as a function of J/t at finite U will be discussed. Our results stem from T=0 quantum Monte Carlo simulations coupled with a recently developed efficient method for the calculation of imaginary time displaced correlation functions [3].
[1] F. F. Assaad, PRL 83, 796 (1999).
[2] S. Capponi and F.F. Assaad, PRB submitted [cond-mat/0010393].
[3] M. Feldbacher and F.F. Assaad, PRB accepted [cond-mat/0009447]