The effect of hydrostatic pressure on magnetostructural transition in ferromagnetic cobaltite: Pr0.6Sr0.4CoO3

The ambient pressure temperature dependence of the magnetization (M) in P1-xSrxCoO3 series (x = 0.4, 0.5, 0.55 and 0.6) indicates the onset of ferromagnetic ordering at high temperatures (TC = 214-226K) and a step-like anomaly at lower temperatures (TS = 69-120 K). In this report we present the pressure dependence of magnetization and zero-field thermal expansion studies for a representative sample x = 0.4. The step-like anomaly in M(T) around TS = 69 K is accompanied by a pronounced peak in thermal expansion coefficient. The application of hydrostatic pressure of P = 1.16 GPa increases TS by 15 K, which is much larger than the increase of the ferromagnetic Curie temperature (ΔTC = 4 K) under the same pressure. The anomalous increase of TS under pressure is attributed to the occurrence of magnetization rotation at a temperature higher than TS = 69 K triggered by the stabilization of low temperature tetragonal phase at the expense of high temperature orthorhombic phase.