Disorder-induced orbital ordering in doped manganites

Abstract

We study the effect of quenched disorder on the ordering of orbital and magnetic degrees of freedom in a two-dimensional, two-band double-exchange model for eg electrons coupled to Jahn-Teller distortions. By using a real-space Monte Carlo method, we find that disorder can induce a short-range ordering of the orbital degrees of freedom near 30% hole doping. The most striking consequence of this short-range ordering is a strong increase in the low-temperature resistivity. The real-space approach allows us to analyze the spatial patterns of the charge, orbital, and magnetic degrees of freedom and the correlations among them. The magnetism is inhomogeneous on the nanoscale in the short-range orbitally ordered state. © 2008 The American Physical Society.