Magnetoresistance of La0.67Ca0.33MnO3 films grown on substrates with orthorhombically distorted unit cells

We have studied the structure and magnetoresistance of 40-nm-thick epitaxial La_0.67Ca_0.33MnO₃ (LCMO) films grown by laser deposition on (001)-oriented NdGaO₃ (NGO) substrates. The manganite layers were oriented so that the b axis was perpendicular to the substrate plane and occurred under the action of inhomogeneous biaxial mechanical stresses. The negative magnetoresistance of the LCMO films in the vicinity of the ferromagnetic spin ordering was about 71% (μ₀ H = 1 T). The observed azimuthal anisotropy of the magnetotransport properties of 40-nm-thick LCMO/(001)NGO films can be explained within the framework of a model of anisotropic magnetoresistance taking into account the presence of the preferred orientation of the spontaneous magnetization.