First-Principles Study of Magnetic Properties and Martensitic Transformation of Pd - Mn - Sn Magnetic Shape Memory Alloys

摘要

Magnetic properties and martensitic transformation of Pd2Mn1+x Sn1-x magnetic shape memory alloys have been investigated by first-principles calculations using the pseudopotentials plane wave method. The formation energy results indicate that the excess Mn atom tends to occupy the Sn site in Pd2MnSn alloy due to the lowest formation energy. It is found that the antiparallel Mn-Sn-Mn-Mn magnetic coupling for x = 0.25 and 0.5 is slightly more stable compared to the parallel coupling. The tetragonal distortion conserving volume shows that the cubic structures for x = 0 and 0.25 are more favorable in energy than the tetragonal phases, whereas the tetragonal structure for x = 0.5 is more stable, indicating that a martensitic transformation from austenite to martensite for x = 0.5 may happen at a lower temperature. Moreover, the martensitic transformation for x = 0.5 is closely related to the enhanced Pd-Mn-Mn hybridization.