A comparative investigation of B-site ordering and structure, magnetic, magnetocaloric effect, critical behavior in double perovskite Nd2BMnO6 (B = Co and Ni)

Abstract In the present work, we have investigated the crystal structure, magnetic, and magnetocaloric properties of the ordered monoclinic polycrystalline double perovskite Nd2BMnO6 (B = Co and Ni). A study of the magnetization dynamics employing temperature and magnetic field shows a powerful spin frustration state with freeing temperature of Tf ~154 K (for Nd2CoMnO6) and Tf ~ 194 K (for Nd2NiMnO6). The ac susceptibility measurements show exhibit frequency- and field-dependent behavior. Both the magnetic relaxation effects and related analysis indicate a typical spin-glass (SG) behavior in Nd2BMnO6. Furthermore, Nd2CoMnO6 (NCMO) and Nd2NiMnO6 (NNMO) show remarkable magnetocaloric effect (MCE) and relative cooling power (RCP) near the paramagnetic (PM) to ferromagnetic (FM) transition. Moreover, the critical behavior is investigated by different theoretical, such as modified Arrott plot (MAP) and Kouvel-Fisher (KF). The critical exponents (β, γ, and δ) of Nd2BMnO6 are obtained from the different methods, which are close to the mean-field model. The detailed analysis on the critical behavior in Nd2BMnO6, which suggests that the long-range FM interaction in the Nd2BMnO6.