The Hall-Lorenz number in the La1.855Sr0.145CuO4 single crystal

摘要

The temperature dependence of the Hall-Lorenz number (L-xy) for the optimally doped La1.855Sr0.145CuO4 (LSCO) has been obtained from the experimentally determined transverse and longitudinal transport coefficients. A comparison between L-xy (T) dependence found for LSCO and L-xy (T) reported previously for copper indicates that the Hall-Lorenz number in LSCO follows standard metallic behavior from room temperature down to T similar to 150 K. Below this temperature the L-xy coefficient deviates from regular metallic dependence in a way characteristic of an electronic system with lowered density of electronic states at the Fermi level. We present results of calculations provided in terms of the Boltzmann equation for a two-dimensional model of the electronic structure with a d-symmetrical pseudogap. A temperature T-max, where a maximum in the L-xy (T) dependence appears, turns out to be dependent on the width of the supposed pseudogap (E-g(max)). The best agreement between the model and the experimental data was obtained for E-g(max) similar to 25 meV, which corresponds well with values reported previously by other groups. (c) 2006 Elsevier Ltd. All rights reserved.