Effects of Eu3+ doping on the structural, magnetocaloric effect and critical behavior of Ruddlesden-Popper compounds La1.4- xEuxSr1.6Mn2O7 (0 < x < 0.1)

The effects of Eu3+ doping on the structural and magnetocaloric effect of Ruddlesden-Popper compounds La1.4- xEuxSr1.6Mn2O7 (0 < x <0.1) were investigated. The X-ray diffraction and infrared spectroscopy confirmed that La1.4- xEuxSr1.6Mn2O7 compounds exhibited the tetragonal lattice symmetry (I4/mmm) of the Ruddlesden-Popper phase. The crystal structure ofLa(1.4- x)Eu(x)Sr(1.6)Mn(2)O(7) compounds distorted and phase separated as the amount of Eu3+ doping varied. The magnetization-temperature curves demonstrated that La1.4- xEuxSr1.6Mn2O7 compounds display a notable transition temperature attributed to its anisotropic exchange coupling. The maximum magnetic entropy changes (- Delta S-M(max)) of La1.4- xEuxSr1.6Mn2O7(x = 0, 0.075, and 0.1) compounds are 2.82, 3.12 and 3.40 J/ (kg & sdot;K) at the 5 T applied magnetic field. Meanwhile, its relative cooling power (RCP) was 186.37, 207.42 and 242.54 J/kg, respectively. The critical behavior of La1.4- xEuxSr1.6Mn2O7 (0 <= x <= 0.1) compounds was analyzed around Tc, and it was found that the critical index(beta = 0.413,gamma = 1.020, delta = 3.038) is essentially in line with the mean field theory.