Magnon drag effect as the dominant contribution to the thermopower in Bi0.5-x Lax Sr0.5 MnO3 (0.1≤x≤0.4)

The temperature-dependent thermopower S (T) of Bi_0.5-x La _x Sr_0.5 MnO₃ (0.1≤x≤0.4) (BLSMO) has been investigated in this study. The density of state at the Fermi level as a function of the La concentration is obtained via the equation for the diffusion thermopower (TEP) in the lowerature regime. An equation that takes into account the diffusion, phonon drag, and magnon drag contributions to the TEP was established. With this equation, each component of the TEP is extracted and compared in the intermediate temperature regime. It was determined that the phonon drag contribution of the TEP is closely related to the La concentration dependence of the lattice parameters and that the magnon drag component contributes predominantly to the thermopower of BLSMO in the intermediate temperature regime. © 2008 American Institute of Physics.