Crystal Structure, Magnetism, and Electronic Properties of a Rare-Earth-Free Ferromagnet: MnPt5As

The design and synthesis of targeted functional materials have been long-term goals for materials scientists. Although a universal design strategy is difficult to generate for all types of materials, it is still helpful for individual families of materials to have such design rules. Herein, we incorporated several significant chemical and physical factors relevant to magnetism, such as structure-type, atomic distance, and spin-orbit coupling, and have thereby successfully synthesized a new rare-earth-free ferromagnet, MnPt5As, for the first time. MnPt5As can be prepared by high-temperature pellet methods. According to the X-ray diffraction results, MnPt5As crystallizes in a tetragonal unit cell with the space group P4/mmm (Pearson symbol tP7). Magnetic measurements on MnPt5As confirm ferromagnetism in this phase with a Curie temperature of similar to 301 K and a saturated moment of 3.5 mu B per formula unit. Evaluation by applying the Stoner criterion also indicates that MnPt5As is susceptible to ferromagnetism. Electronic structure calculations using the WIEN2k program with local spin density approximation imply that the spontaneous magnetization of this phase arises primarily from the hybridization of the d orbitals on both Mn and Pt atoms. The theoretical assessments are consistent with the experimental results. Moreover, spin-orbit coupling effects heavily influence the magnetic moments in MnPt5As. MnPt5As is the first ferromagnetic material in the MgPt5As structure-type. The discovery of MnPt5As offers a platform to study the interplay between magnetism and structure.