Computational analysis of anomalous temperature dependence of magnetic properties in Mn4C compound

Highlights: • Origin of phase stability of metastable Mn₄C was investigated using density of states. • We have calculated exchange integrals and Curie temperature for the Mn₄C. • The Brillouin functions for the two magnetic sublattices were built. • Temperature dependences of the two magnetic sublattices were calculated. • The calculated total magnetization well agrees with experimental values with temperature. We have calculated electronic structures of Mn₄C using first-principles calculations based on density functional theory (DFT) within the Perdew Burke Ernzerhof-generalized gradient approximation (PBE-GGA). The calculated band structures and density of states (DOS) indicate that stability of cubic perovskite-type crystal structured Mn₄C is originated from p-d hybridization between Mn_b and C and d-d hybridization between Mn_a and Mn_b sublattices. The mean field approximation (MFA) resulted in the Néel temperature (T_N) of 879 K which is in close agreement with experimental T_N. The temperature dependence of magnetic moments of Mn_a and Mn_b sublattices were also calculated using the Brillouin function to investigate the origin of unusual linearly increasing magnetization below 400 K. It was found that the increasing magnetization is originated from strong mutual interdependence of more or less linearly decreasing magnetic moment of Mn_a and stationary magnetic moment of Mn_b below 400 K.