A variational study of electronic thermal conductivity of Anderson lattice model: an application to CMR manganites (Re_1-xA_xMnO₃)

Using the variational method, we have investigated the temperature dependence of the electronic thermal conductivity (k_el) in rare-earth manganites doped with alkaline-earth ions, which display the well-known CMR behavior. The analysis is based on a two-band (l − b) Anderson lattice model Hamiltonian appropriate for the strong electron-lattice Jahn–Teller (JT ) coupling regime, consistent with two-fluid descriptions incorporating (l −b) hybridization. Key model parameters includes Coulomb repulsion U , strong Hund’s coupling JH between e_g and t_2g spins and hybridization V between l-polarons and d-electrons of the same spin. In the ferromagnetic metallic phase, calculations show that the kel increases with increasing temperature and near the transition temperature T_c ≈ 400 K, it shows a minimum or a dip in k_el for a fixed value of V , J_H and x. The results of k_el exhibit a typical crystalline character with grain boundary scattering as a main mechanism limiting the heat transfer in these compounds.

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