Electrical resistivity in the ferromagnetic metallic state of La-Ca-MnO$\mathsf{_{3}}$: Role of electron-phonon interaction

Abstract.

The temperature-dependent resistivity of the perovskite manganites La_1-x Ca _x MnO₃, with x = 0.33, is theoretically analysed within the framework of the classical electron-phonon model of resistivity, i.e., the Bloch-Gruneisen model. Due to inherent acoustic (low-frequency) phonons ($\omega_{ac})$ as well as high-frequency optical phonons ($\omega_{op})$, the contributions to the resistivity have first been estimated. The acoustic phonons of the oxygen-breathing mode yield a relatively larger contribution to the resistivity compared to the contribution of optical phonons. Furthermore, the nature of phonons changes around T = 167 K exhibiting a crossover from an acoustic to optical phonon regime with elevated temperature. The contribution to resistivity estimated by considering both phonons, i.e. $\omega_{ac}$ and $\omega_{op}$, when subtracted from thin film data, infers a power temperature dependence over most of the temperature range. The quadratic temperature dependence of $\rho_{\it diff.} = [ \rho_{\exp} . - \{\rho_{0} + \rho_{e\text{-}ph} (= \rho_{ac} + \rho_{op}) \} ]$ is understood in terms of electron-electron scattering. Moreover, in the higher temperature limit, the difference can be varies linearly with T ^4.5 in accordance with the electron-magnon scattering in the double exchange process. Within the proposed scheme, the present numerical analysis of temperature dependent resistivity shows similar results as those revealed by experiment.