The role of stepped surfaces on the magnetotransport in strained thin films of La0.67Ca0.33MnO3

We report a comparative study of the properties of very thin films of La0.67Ca0.33MnO3 grown epitaxially under strain on flat SrTiO3 (STO) and on 1 deg miscut STO. For the films on flat STO the transport properties show well-known behavior, namely values of the metal-insulator transition temperature which are strongly reduced with respect to the bulk value. The reduction in films on miscut STO is significantly less strong than in films on flat STO, even though they appear similar as to strain state. Moreover, the residual resistance at low temperatures is lower than for the case of flat films. Magnetically, we find reduced values of the saturation magnetization with respect to the bulk value, indicating the presence of a dead layer in both cases. We argue that the higher density of the step edges on the miscut substrates lead to strain relaxation in the form of point defects and an increased electronic bandwidth, which actually make the electronic properties more robust.