Magnetic and magnetocaloric properties of monovalent (Li +1 ) doped PrMnO 3 : a study by Maxwell relation and Landau theory

Detailed investigation of magnetic properties and magnetocaloric behavior of monovalent doped Pr 0.75 Li 0.25 MnO 3 has been carried out. Doping of monovalent Li cation at the Pr site reduces the strength of antiferromagnetic interaction of pristine PrMnO 3 compound. Antiferromagnetic spin ordering is disturbed due to the emergence of double exchange favoured ferromagnetic component. Room temperature paramagnetic (PM) Pr 0.75 Li 0.25 MnO 3 sample becomes antiferromagnetic (AFM) at 28 K followed by a low-temperature negative magnetization region below 7 K. Analysis of isothermal magnetization data through Arrott plot reveals that Pr 0.75 Li 0.25 MnO 3 sample suffers 2nd order magnetic phase transition. Isothermal magnetic entropy changes at different temperatures have been evaluated for a range of values of the magnetic field by integrating thermodynamic Maxwell’s relation numerically and utilizing isothermal magnetization data. The magnetic entropy change curve for a magnetic field of 5 T shows peak at 42 K and the maximum value of magnetic entropy change is found to be 2.54 J-kg − 1 K − 1 . The experimentally determined magnetic entropy change curve matches well with the theoretical magnetocaloric effects (MCE) curve. Calculation based on Landau theory establishes that electron interaction and magnetoelastic couplings can well describe temperature-dependent magnetic entropy changes at different magnetic fields in Pr 0.75 Li 0.25 MnO 3 manganite.