Effect of ru-doping on magnetocaloric effect in Pr based charge ordered manganites

Abstract

It is shown that charge-orbital ordered antiferromagnetic state of the parent compound (x=0) in Pr0.5Ca0.5Mn1-xRu xO3 series is destabilized and ferromagnetism is induced by Ru doping, as small as 3%, at the Mn site. The ferromagnetic transition temperature (TC) increases with Ru content from TC=213 K for x=0.03 to 239 K for x=0.1 but the field dependence of magnetization does not show metamagnetic transition above or below TC unlike Pr 0.5Ca0.5Mn1-xCrxO3. The change in magnetic entropy (ΔSM) is the largest for x=0.03 (ΔSM=-4.2 J/kg K at 213 K for ΔH=5 T) and decreases with increasing Ru content (ΔSM=-3.8 J/kg K at 221 K and -3.4 J/kg K at 239 K for ΔH=5 T, for x=0.05 and 0.10, respectively). However, the relative cooling power increases with Ru content from 284.9 J/kg for x=0.03 to 303.6 J/kg for x=0.1. The large magnetic entropy change found in x=0.03 and the absence of high field hysteresis in M-H curves make the Ru-doped samples suitable candidates for magnetic refrigeration. © 2006 IEEE.