Investigation on phase structure and magnetic properties of high-temperature Ni-Pt-Co-Mn-Sn magnetic shape memory alloys by first-principles calculations

Ni-Mn-Sn ferromagnetic shape memory alloys (FSMAs) as multi-functional materials have attracted great attention due to the magnetic field-induced reverse martensitic transformation (MFIRMT). However, it is still a challenge to achieve a high working temperature in this material. Here, we propose a Pt and Co co-doping method to realize the high working temperature of FSMAs materials. Butmostimportantly, the effect of Pt and Co doping cannot be added up simply because they have different influence trends on the working temperature in Ni-Mn-Sn alloys. To balance their influence is the critical step. We use the first principles to calculate and predict the effects of Pt and Co co-doping on the martensitic transformation temperature (TM), Curie temperature (TC), and the difference of magnetization (ΔM) in Ni16-x-yPtxCoyMn13Sn3 (x = 3, 4; y = 1, 2, 3). According to the prediction results, we reported that Ni11Pt3Co2Mn13Sn3 and Ni9Pt4Co3Mn13Sn3 show a large ΔM in the high-temperature environment (above 370 K). Particularly, the working temperature of Ni11Pt3Co2Mn13Sn3 reaches the highest temperature (~440 K) in Ni-Mn-Sn alloys. Hence, Ni11Pt3Co2Mn13Sn3 is expected to become a new type of high-temperature FSMAs. This Pt and Co co-doping method in Ni-Mn-Sn alloys provides an ideal strategy to discover new high-performance FSMAs.