High Temperature Thermopower in La_{2/3}Ca_{1/3}MnO_3 Films: Evidence for Polaronic Transport

Abstract

Thermoelectric power, electrical resistivity and magnetization experiments, performed in the paramagnetic phase of La_{2/3}Ca_{1/3}MnO_3, provide evidence for polaron-dominated conduction in CMR materials. At high temperatures, a large, nearly field-independent difference between the activation energies for resistivity (rho) and thermopower (S), a characteristic of Holstein Polarons, is observed, and ln(rho) ceases to scale with the magnetization. On approaching T_c, both energies become field-dependent, indicating that the polarons are magnetically polarized. Below T_c, the thermopower follows a law S(H) prop. 1/rho (H) as in non saturated ferromagnetic metals.

arXiv comment10 pages, 5 .gif figures. Phys. Rev B (in press)

References in corpus (1)

• Double Exchange Alone Does Not Explain the Resistivity of $L{a}_{1-x}S{r}_{x}Mn{O}_3$

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