Effect of strain on the transport and magnetoresistance properties of La0.8Ca0.2MnO3 epitaxial thin films

Abstract

The true residual stress in La0.8Ca0.2MnO3 (LCMO) thin films of various thicknesses deposited on STO substrates under the same deposition conditions was measured quantitatively by x-ray diffraction sin2ψ method. The truly strain-induced effect on the transport and magnetoresistance (MR) properties of LCMO films was investigated. The in-plane residual stress (σ11) in the LCMO film is tensile, while the out-of-plane one (σ33) is compressive. Moreover, the value of σ33 is larger than that of σ11. With increasing film thickness, the crystalline unit cell of the LCMO film reduces; also both the in- and out-of-plane components of the residual stress in the LCMO film decrease. It was found that the resistivity, TMI and MR strongly depend on the in-plane tensile stress σ11 (or/and the out-of-plane stress σ33). With the increase in the in-plane stress σ11 (or/and the out-of-plane stress σ33), the values of resistivity and MR increase, while TMI decreases. The truly strain-induced effect on the transport and magnetoresistance properties of LCMO film is discussed briefly.