Thickness dependent magnetic and magnetotransport properties of strain-relaxed La_0.7Ca_0.3MnO₃ films

La_0.7Ca_0.3MnO₃ films with thicknesses between 2 and 300 nm were fabricated on LaAlO₃, SrTiO₃, and (LaAlO₃)_0.3(Sr₂AlTaO₆)_0.7 (LSAT) substrates using pulsed laser deposition. After annealing at 950 °C in flowing oxygen, on LaAlO₃ and LSAT, strain-relaxed epitaxial films of high quality were obtained. The magnetization, resistivity, and magnetoresistance of the films was studied as a function of thickness. Down to a thickness of about 4 nm no decrease of the saturation magnetization could be detected; the Curie temperature decreases slightly with thickness in agreement with finite size scaling theory. The thickness dependence of the conductance can be understood as a size-effect in thin films; there is no indication of an electrically dead interfacial layer. © 2002 American Institute of Physics.