Possible manifestation of spin fluctuations in the temperature behavior of resistivity in Sm_{1.85}Ce_{0.15}CuO_4 thin films

TL;DR

This study observes a kink in resistivity at 87K in Sm_{1.85}Ce_{0.15}CuO_4 thin films, attributed to spin fluctuations from Sm^{3+} moments, and models the data considering various scattering contributions.

Contribution

It provides evidence of spin fluctuation effects in resistivity and offers a detailed fitting model including multiple scattering mechanisms in electron transport.

Findings

Resistivity exhibits a kink at 87K linked to spin fluctuations.

The data fit well with models including residual, electron-phonon, and electron-electron contributions.

Estimated parameters include plasmon frequency, impurity scattering rate, electron-phonon coupling, and Fermi energy.

Abstract

A pronounced step-like (kink) behavior in the temperature dependence of resistivity $\rho (T)$ is observed in the optimally-doped $Sm_{1.85}Ce_{0.15}CuO_4$ thin films around $T_{sf}=87K$ and attributed to manifestation of strong spin fluctuations induced by $Sm^{3+}$ moments with the energy $\hbar \omega_{sf}=k_BT_{sf}\simeq 7meV$. In addition to fluctuation induced contribution $\rho_{sf}(T)$ due to thermal broadening effects (of the width $\omega_{sf}$), the experimental data are found to be well fitted accounting for residual (zero-temperature) $\rho_{res}$, electron-phonon $\rho _{e-ph}(T)=AT$ and electron-electron $\rho_{e-e}(T)=BT^2$ contributions. The best fits produced $\omega_p=2.1meV$, $\tau_0^{-1}=9.5\times 10^{-14}s^{-1}$, $\lambda =1.2$, and $E_F=0.2eV$ for estimates of the plasmon frequency, the impurity scattering rate, electron-phonon coupling constant, and the Fermi energy, respectively.