Structure and Thermal-enhanced Magnetic Properties of Mn4C Melt-spun Ribbons with Varied Stoichiometry

Cubic perovskite-type Mn4C is difficult to prepare for its metastable characteristics. In this work, we have obtained high-purity Mn4C successfully by using melt-spinning method. The effects of stoichiometry on the structure and magnetic properties of the samples were studied systematically. We found that x = -0.1 is the optimum composition for the formation of the cubic perovskite phase in Mn4+xC during rapid quenching. Most Mn4+xC melt-spun ribbons with x other than -0.1 are composed of Mn23C6, alpha-Mn, and Mn4C, while the fraction of different phase in Mn4+xC ribbons varies with x. The Curie temperature of Mn4+xC ribbons increases slightly with decreasing x, which may affect the lattice parameters of cubic Mn4C and thus the Mn-Mn exchange interactions. The magnetization of Mn4+xC ( x = -0.1 and 0) increases with increasing temperature in high-temperature region while the onset temperature for such behavior is dependent on the fraction of Mn4C in the samples.