Strain Effect of Lan-nxCa1+nxMnnO3n+1 Thin Films

The electrical and magnetic properties, including the magnetoresistance (MR) effect, of Lan-nxCa1+nxMnnO3n+1 thin films (n = ∞, 2; x = 0.3) grown on various substrates were investigated. For n = 2 (La1.4Ca1.6Mn2O7) thin films, the cusp temperature (Tcρ) in the ρ-T curve decreased very sharply with a decrease of the out-of-plane lattice parameter (a). The MR effect was enhanced drastically by decreasing Tcρ. These behaviors are interpreted in relation to the change in the transport character along the c-axis due to the strain.