Effect of cobalt substitution on magnetic and transport properties of Nd0·5Sr0·5Mn1−x Co x O3 (x = 0·1, 0·3 and 0·5)

Abstract

The magnetic and transport properties of the compounds Nd0·5Sr0·5Mn\(_{{\rm 1}-{x}}\)Co\(_{{x}}\)O3 (x = 0·1, 0·3 and 0·5), synthesized by citrate–gel route have been investigated. The spin transition in cobaltates at low temperatures affects the magnetic as well as transport properties. The irreversibility behaviour between the zero-field cooled (ZFC) and field cooled (FC) magnetization as a function of temperature becomes stronger with increasing Co content. This is understood on the basis of glassy behaviour, which becomes more robust with increasing Co substitution. The non-saturating M–H behaviour indicates strong magnetic inhomogeneities which may cause the magnetic phase separation at the nanoscopic length scale. The double exchange interaction is stronger between Mn3 + –O2 − –Mn4 + as compared to Co3 + –O2 − –Co4 + pairs. Co-substitution suppresses the double exchange which will lead to cluster/spin glass like behaviour as well as semiconducting features due to localization of charge carriers (mobile \({e}_{\rm g}\) electrons).