Electronic phase separation and the CMR effect in Pr 1− xCa xMnO 3 films on (0 0 1) vicinal SrTiO 3 substrates

Abstract

Our previous work showed that Pr 1− x Ca x MnO 3 ( x = 0.2–0.5) thin films reveal an electronic phase separation, in which the low-temperature phase is orbital- and charge-ordered of the Zener-polaron type [Ch. Jooss, T. Beetz, L. Wu, M. Beleggia, R. Klie, M. Schofield, Y. Zhu, S. Schramm, J. Hoffmann, submitted for publication]. Applying a magnetic field leads to a ferromagnetic and conducting phase, which gives rise to the colossal magneto resistance effect (CMR). In this article we show that the orbital- and charge-ordered state could be significantly modified by different kind of lattice defects. Quenched disorder, present after the film deposition, can suppress long-range ordering. In addition, extended defects like twin boundaries act as a nucleation center for ordered domains, i.e. the hysteretic properties depend on the density of these defects. Well-ordered artificial anti-phase boundaries (APB) can be introduced by an epitaxial growth on vicinal substrates, leading to anisotropic transport properties with respect to the orientation of the APB.