Thermoelectric power of polycrystalline hole and electron doped manganites

Abstract

The temperature dependence of the thermoelectric power S(T) for polycrystalline hole-doped La0.8Ca0.2MnO3 and electron doped La0.8Ce0.2MnO3 perovskites have been investigated to determine the role of several scattering mechanism. In the ferromagnetic regime, the phonon drag S(T) with scattering of phonons from defects, grain boundaries, phonons and charge carriers in these samples is computed within the relaxation time approximation. Later on, Mott expression is used to generate the carrier diffusive thermoelectric power. It is noticed that the behaviour of the S(T) is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions in the hole-doped and electron doped samples. © 2007 IOP Publishing Ltd.