Observation of mixed-phase behavior in the Mn-doped cobaltite La0.7Sr0.3Co1−xMnxO3 (x=0–0.5)

Abstract Studies on La 0.7 Sr 0.3 Co 1− x Mn x O 3 ( x =0–0.5) compounds evidence that the interaction between Mn and Co ions in this system is antiferromagnetic super-exchange and not ferromagnetic (FM) double-exchange (DE). As a result, antiferromagnetism and magnetic glassiness develop steadily with increasing Mn content and the system becomes a spin glass at x ∼0.1. Analyses of high-field magnetization data indicate that the system consists of two major phases: a metallic FM phase which magnetically saturates in rather low field, and an insulating non-FM phase which has a linear dependence of magnetization on magnetic field. In the low doping regime, the fraction of the non-FM component expands with temperature at the expense of the FM phase and becomes maximal at T C . Ferromagnetism reappears in highly doped ( x ≥0.2) compounds due to the presence of DE interaction between the Mn ions. The small volume fraction of the FM phase derived from the M ( H ) data in high-field region supports the coexistence of insulating and FM behaviors in the highly doped samples.