Spin-wave scattering at low temperatures in manganite films

Abstract

The temperature $T$ and magnetic field $H$ dependence of the resistivity $ρ$ 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 $ρ$ in the ferromagnetic metallic region follows well $ρ(H,T)=ρ_{0}(H)+A(H)ω_{s}/\sinh (\hbar ω_{s}/2k_{B}T)+B(H)T^{7/2}$ with $ρ_{0}$ 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