Spin-wave scattering at low temperatures in manganite films

Abstract

The temperature $T$ and magnetic field $H$ dependence of the resistivity $\rho$ has been measured for La${}_{0.8-y}$Sr${}_{0.2}$MnO${}_3$ (y=0 and 0.128) films grown on (100) SrTiO${}_3$ substrates. The low-temperature $\rho$ in the ferromagnetic metallic region follows well $\rho (H,T)={\rho }_0(H)+A(H){\omega }_s/\sinh (\hslash {\omega }_s/2k_{B}T)+B(H)T^{7/2}$ with ${\rho }_0$ being the residual resistivity. We attribute the second and third term to small-polaron and spin-wave scattering, respectively. Our analysis based on these scattering mechanisms also gives the observed difference between the metal-insulator transition temperatures of the films studied. Transport measurements in applied magnetic field further indicate that spin-wave scattering is a key transport mechanism at low temperatures.

5 pages, 4 figures. to appear in Phys. Rev. B