|DATE||September 18 (Tue), 2018|
|TITLE||The charge density wave in LuP2 In (P = Pd, Pt) mediated by electron phonon coupling|
We have explored the charge density wave (CDW) instabilities in LuPd2In and LuPt2In cubic-Heusler compounds using band structure and phonon dispersion calculations based on the ab initio density functional theory. We have found a dominant Fermi-surface (FS) nesting vector of qM = (0.5, 0.5, 0.0) for both compounds. However, the phonon softening instability occurs only for LuPt2In as is consistent with experimental result. We have demonstrated that the presence and the absence of CDW instabilities, respectively, in LuPt2In and LuPd2In originate not from the difference in the FS nesting or the spin-orbit coupling strength but from the difference in the electron-phonon coupling strength. In the CDW ground states, Pt ions in LuPt2In are distorted into Pt cubes, which have a rotation within the Heusler structure. This transition induces the suppression of density of state of Pt d-band near the Fermi level.