Griffiths phase and magnetocaloric behaviour in electron doped Ca0.85Sm0.15MnO3

Abstract

Magnetic and magnetocaloric properties of electron doped manganite Ca0.85Sm0.15MnO3(CSMO) synthesized by conventional solid state reaction route are studied. By Sm doping at the Ca site the long range antiferromagnetic ordering of the pristine CaMnO3 sample is disturbed and ferromagnetism is induced. The polycrystalline CSMO sample undergoes ferromagnetic to paramagnetic transition at a temperature of 115 K. In addition to the positive slopes of the Arrot plots, the excellent fit of the magnetization data with the Equation of state and the positive value of the Landau coefficient B(T) indicates 2nd order magnetic phase transition. The presence of the Griffiths phase (GP) was identified from the susceptibility study of the sample and the GP characteristic is suppressed with increasing applied magnetic field strength. Temperature dependent magnetic entropy changes for different magnetic fields have been determined using numerical integration of Maxwell's relation based on experimental magnetization data. The maximum magnetic entropy change is found to be 0.61 J-kg−1k−1 for a magnetic field change of 10 kOe. The magnetic entropy change curves at different applied magnetic field collapsed onto a single universal curve. This further confirms that the studied sample undergoes a 2nd order magnetic phase transition.