Effect of hydrostatic pressure on magnetic entropy change and critical behavior of the perovskite manganite La0.4Bi0.3Sr 0.3MnO3

Abstract

We report the effect of magnetic field (H) and hydrostatic pressure (P) on the order of magnetic transition of polycrystalline La0.4Bi 0.3Sr0.3MnO3 which undergoes a first-order paramagnetic (PM) to ferromagnetic (FM) transition in La0.7-xBi xSr0.3MnO3 series. The ferromagnetic Curie temperature (TC) increases with increasing H (12.01 K/T-cooling and 10.28 K/T-warming) and P (8.1 K/kbar-cooling and 6 K/kbar-warming). The first-order FM transition becomes second-order under the applied magnetic field of 9 T and pressure of 9.1 kbar. We have analyzed the critical behavior associated with the second order PM-FM transition at 9.1 kbar. The estimated critical exponents (β = 0.5217, γ = 1.209, and δ = 3.162) are found to be close to the mean-field model. Pressure suppresses metamagnetic transition in magnetization isotherms observed above TC in ambient pressure and enhances the magnetic entropy change (ΔSm). The ΔSm was found to increase by 50% under hydrostatic pressure of 9.1 kbar at TC = 240 K. This study suggested that hydrostatic pressure can be used to enhance magnetocaloric values in phase separated manganites. © 2013 American Institute of Physics.