Dresden 2006 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.26: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Heat capacity and spin susceptibility of two-dimensional t-J model — •Marina Poltavskaya, Tatiana Antsygina, Konstantin Chishko, and Igor Poltavsky — B. Verkin Institute for Low Temperature Physics and Engineering, Kharkov, Ukraine

Thermodynamic properties of the two-dimensional t-J model on square and triangular lattices near half-filling are investigated theoretically within an analytical approach based on the Kondo and Yamaji’s Green function decoupling scheme. The assumption is made that in the system under study two types of elementary excitations exist: "spin wave-like" ones and those corresponding to the correlated motion of the holes. It is shown that these excitations are effectively separated if the hopping amplitude t is less than the exchange constant J. For this case the temperature dependences of the heat capacity and spin susceptibility are calculated in the wide temperature range. It was found, that with the increase of doping from the half-filling the maximum of the spin susceptibility increases and its position shifts to lower temperatures for both types of lattices. Such behavior is in agreement with the qualitative predictions made in [1]. Heat capacity demonstrates a double peak shape. The high temperature peak is associated with the "spin wave-like" excitations and shifts to lower temperatures with doping. The low temperature peak appears due to the holes and its height and position depend on both the doping and ratio t/J.

0.2cm 1. E. Dagotto Rev. Mod. Phys., 66, 763 (1994).