Variation of charge-orbital correlation with Cr doping in manganites

Abstract

The stability of charge-orbital ordering in a colossal magnetoresistance (CMR) manganite can be varied to a large extent by doping of Cr impurities on the Mn site. Most of the generic features seen in the CMR manganites, such as the submicrometric phase separation into metallic and insulating states, a resistivity-enhanced paramagnetic state, and related CMR effect, can be generated successively with Cr doping in ${\mathrm{Nd}}_{1/2}{\mathrm{Ca}}_{1/2}{\mathrm{MnO}}_3$ crystal. Systematic studies of the Cr-doped crystals by measurements of magnetotransport and x-ray diffraction have shown that the incommensurate charge-orbital-ordered state turns into the dynamic and short-range charge-orbital correlation that is the origin of the high-resistive state exhibiting CMR.