DFT plus U study of the bulk and (001), (110) and (111) surfaces of NaCrAs half-Heusler alloy with hydrogen adsorption for spintronics applications

摘要

In order to implement the Heusler alloys in spintronic devices, the half-metallic property should be preserved at the surfaces even with contamination elements that may be present in the residue gas during the deposition processes. Therefore, we have considered the bulk and surface properties of NaCrAs with contamination H elements using DFT + U approximation. It is found that NaCrAs is a half-metal with the magnetic moment of 4 mu(B). Much of the magnetic moment arises from Cr atoms and the hybridization between the d orbitals of Cr with the p orbitals of As gives rise to the half-metallic property. The Curie temperature is estimated to be well above the room temperature and the half-metallicity is preserved in a rather wide range of the lattice parameter. The vibrational properties of the specimen are also considered by phonon spectrum calculation, which confirms the stability of the sample. The electronic and magnetic properties of (001), (110) and (111) surfaces with the hydrogen adsorption are also investigated, and it is found that half-metallicity is well retained at all of the surfaces. The excellent bulk and surface properties of this new material lead us to conclude that it is a very appropriate candidate for the spintronics applications.