Abstract
Pressure effect on magnetic properties of La0.9Ba0.1CoO3 cobaltite, exhibiting the ferromagnetic (FM) cluster-glass behavior and exchange bias (EB) effect at low temperatures, was investigated up to 10 kbar. It was found that an applied pressure increases the temperature TCcl ≈ 190 K, below which the FM clusters appear, and enlarges the FM phase volume in the sample. Positive value of dTCcl/dP coefficient suggests a wide eg-electron bandwidth for Co ions sited inside the Ba-rich regions (FM clusters). The EB field HE increases sharply with decreasing temperature below the spin-glass (SG) like transition temperature Tf ≈ 38 K, in a consequence of the exchange coupling at the FM/SG interfaces. Applied pressure was found to suppress strongly the EB, in particular, HE reduces by a factor of ∼3 under pressure of 10 kbar at 30 K. It appears that under pressure, HE varies oppositely to the changes in FM phase volume that is very similar to the behavior observed for phase-separated FM/antiferromagnetic manganites. Overall, the pressure-induced diminution in HE is explained by considering an increase of the FM cluster size and by concomitant decrease of distance between clusters. The results show that for phase-separated FM/SG cobaltites, the EB effect may be controlled by external pressure.
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