Emergence of Griffiths phase and magnetocaloric behavior in electron doped Ca_0.85Nd_0.15MnO₃

A detailed study of temperature and magnetic field dependent magnetic properties of electron doped polycrystalline manganite Ca_0.85Nd_0.15MnO₃ (CNMO) has been reported. Nd doping at the Ca site induces ferromagnetism through the interruption in the long range antiferromagnetic spin ordering of pristine CaMnO₃. Room temperature paramagnetic CNMO sample becomes ferromagnetic at 115 K. Analysis of isothermal magnetization data through Arrott plot reveals that CNMO sample undergoes 2nd order magnetic phase transition. Study on magnetic susceptibility exposes that Griffiths phase is present in CNMO manganite. Magnetic entropy changes as a function of temperature at different values of magnetic field changes have been evaluated by integrating Maxwell's thermodynamic relation numerically and using isothermal magnetization data. For a magnetic field change of 30 kOe the value of maximum magnetic entropy change is found to be 0.816 J kg^− 1k^− 1. After rescaling, coincidence of all temperature dependent magnetic entropy change curves for different magnetic field leads to a universal curve. This further establishes that the magnetic phase transition in polycrystalline CNMO sample is a 2nd order phase transition.