Hamburg 2001 – scientific programme

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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 6.15: Poster

Monday, March 26, 2001, 14:30–17:00, Rang S\ 3

Spin-Gap and charge dynamics in chains and ladders — •L. Campos Venuti and A. Muramatsu — Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart

We study the consequences of hole doping in correlated chains and ladders. Starting from the Spin-Fermion model we construct an effective field theory where the charge carriers are minimally coupled to a gauge field whose fluctuations are controlled by the CP¹ model. On the other hand, integrating out the fermions, we obtain an effective action for the spins in terms of a Fermi determinant. This is evaluated in the long-wavelength, low-frequency limit. The result is a non-linear sigma model with a coupling constant that depends on the concentration of dopant holes through generalized susceptibilities of the fermionic system. Such a procedure makes possible to calculate the behavior of the spin gap (for the 2LL case) as a function of doping.