First-Principles Study on a New All-d-Metal Full-Heusler-Based Shape-Memory Alloy Cd₂MnPd

Abstract

A new all-[Formula: see text]-metal full-Heusler alloy (Cd2MnPd) was designed based on density functional theory. Its crystal structure, band structure, density of states, magnetism, and the possibility of martensitic transformation were studied. The calculated total energy shows that the most stable cubic structure of this alloy is the L21 type at ferromagnetic (FM) state, and the equilibrium lattice constant is 6.57[Formula: see text]Å. The band structure and density of states show that it is a FM metal with a total magnetic moment of 3.97[Formula: see text][Formula: see text], mainly originating from the Mn element. The results of the martensitic transformation investigation show that the martensitic phase has minimum energy when the c/a ratio is 1.35, and the absolute value of the energy difference ([Formula: see text]) between the martensitic and the austenitic phases is 0.07[Formula: see text]eV. This indicates that there is a high possibility that a stable martensitic phase exists. Furthermore, [Formula: see text] can be tuned by uniform strain, and the absolute value of [Formula: see text] increases as the volume increases in the range of [Formula: see text] ([Formula: see text] is the optimal volume, namely, the cubic volume under its equilibrium lattice). In conclusion, Cd2MnPd may be a good candidate for ferromagnetic shape-memory alloys (FSMAs). We expect that our theoretical prediction can provide guidance for exploring valuable FSMAs experimentally.

All-d-Metal Full Heusler Alloys: A Novel Class of Functional Materials

“…The results confirmed the trend of L2 1 austenite with FM ordering as the most energetically stable configuration. Similar results have been found by Chen et al 76 for Cd 2 PdMn for which the Cd (4d 10 5s 2 ) atom, with the highest relative electronic valence, occupies (A/C) sites, while Pd (4d 8 5s 2 ) and Mn (3d 5 4s 2 ) occupy, respectively, (B) and (D) sites, also displaying FM ordering. For the cases above, the Mn(D) carries most of the magnetic moment, and the Mn(D)− Mn(D) coupling is expected to result in FM ordering since the interatomic distance is identical with the Mn(B)−Mn(B) interatomic distance for an L2 1 structure (see Figure 2b).…”