Experimental and theoretical study of magnetization and magnetocaloric effect in Nd1−xSmxFeO3

Abstract

We have experimentally and theoretically investigated the magnetic properties and magnetocaloric effect in doped orthoferrite series Nd1−xSmxFeO3 (x = 0, 0.1, and 0.4). Our magnetization measurements reveal that the spin-reorientation transition temperatures of the Fe3+ moments increase as a function of Sm doping. Our measurements on the magnetocaloric effect indicate that the effect [measured by the maximum change in magnetic entropy (−ΔSM)] reduces with Sm doping. Non-collinear calculations including the effect of Coulomb correlation (U) and spin–orbit interaction (SO) were performed within the GGA + U + SO approximation using the first-principles density functional theory (DFT) to establish the magnetic structure above and below the spin-reorientation transition. Calculations of the exchange interaction strengths using DFT reveal a higher strength of Sm–Fe exchange interaction than that of Nd–Fe interaction, which explains the higher spin-reorientation transition temperatures observed in the doped compounds. Using Monte Carlo calculations on the Ising model with large moments of Nd/Sm, we have extracted the effective nearest neighbor exchange interaction values between rare-earth moments, which provide good agreement with the corresponding experimental results on −ΔSM around and below the transition temperature.