Effect of lateral tensile stresses on the low-temperature electrical resistivity and magnetoresistance of La0.67Ca0.33MnO3 nanofilms

Abstract

The thickness of the buffer layer of strontium titanate introduced between an La0.67Ca0.33MnO3 manganite film and a (001)La0.29Sr0.71Al0.65Ta0.35O3 substrate is varied (d1 = 7–70 nm) to influence effective misfit m in their lattice parameters. As m increases, electrical resistivity ρ of the film increases sharply and the maximum in the ρ(T) dependence shifts toward low temperatures. At T < 150 K, the temperature dependence of ρ of the manganite film obeys the relationship ρ = ρ1 + ρ2T4.5, where parameter ρ1 is independent of the temperature and magnetic field. Coefficient ρ2 decreases with increasing magnetic field and increases with the misfit between the lattice parameters of the film and substrate, i.e., when the effective hole concentration in the manganite layer decreases.