Enhancing the magnetization of Mn4C by heating

Abstract

Little is known about the physical properties of Mn4C for which is unstable and difficult to prepare. We herein report on the unusual thermomagnetic properties of high purity Mn4C powders obtained by plasma melting and magnetic separation processes. The saturation magnetization of Mn4C increases linearly with increasing temperature in the range of 50 K-590 K and remains stable at temperatures below 50 K. The anomalous magnetization increases of Mn4C with increasing temperature can be considered in terms of the Néel's P-type ferrimagnetism. At temperatures above 590 K, the Mn4C decomposes into Mn23C6 and Mn, which would be partially oxidized into manganosite when exposed to air. The remanent magnetization of Mn4C varies little with temperature. The Curie temperature of Mn4C is around ∼870 K. The positive temperature coefficient (∼0.0072 Am2 kg-1 K-1) of magnetization in Mn4C makes it potentially important in controlling the thermodynamics of magnetization in magnetic materials.