Crystal Symmetry, Electron-Phonon Coupling, and Superconducting Tendencies in Li$_2$Pd$_3$B and Li$_2$Pt$_3$B

K. -W. Lee; W. E. Pickett

doi:10.1103/PhysRevB.72.174505

paper

Crystal Symmetry, Electron-Phonon Coupling, and Superconducting Tendencies in Li $_{2}$ Pd $_{3}$ B and Li $_{2}$ Pt $_{3}$ B

arXiv:cond-mat/0507105 · doi:10.1103/PhysRevB.72.174505

Abstract

After theoretical determination of the internal structural coordinates in Li $_{2}$ Pd $_{3}$ B, we calculate and analyze its electronic structure and obtain the frequencies of the two $A_{g}$ phonons (40.6 meV for nearly pure Li mode, 13.0 meV for the strongly mixed Pd-Li mode). Pd can be ascribed a $4 d^{10}$ configuration, but strong 4d character remains up to the Fermi level. Small regions of flat bands occur at -70 meV at both the $Γ$ and X points. Comparison of the Fermi level density of states to the linear specific heat coefficient gives a dynamic mass enhancement of $λ$ = 0.75. Rough Fermi surface averages of the deformation potentials $D$ of individual Pd and Li displacements are obtained. While < $D_{L i}$ > is small, < $D_{P d} > 1.15 e V / A ˚ i ss i z ab l e, an d a pl a u s ib l ec a see x i s t s f or i t ss u p er co n d u c t i v i t y a t 8 K b e in g d r i v e n p r ima r i l y b y co u pl in g t o P d v ib r a t i o n s . T h e l a r g er d ban d w i d t hin L i$ _2 $P t$ _3$B leads to important differences in the bands near the Fermi surface. The effect on the band structure of spin-orbit coupling plus lack of inversion is striking, and is much larger in the Pt compound.

8 pages and 8embedded figures, to be appeared in PRB

Crystal Symmetry, Electron-Phonon Coupling, and Superconducting Tendencies in Li2​Pd3​B and Li2​Pt3​B

Abstract

Crystal Symmetry, Electron-Phonon Coupling, and Superconducting Tendencies in Li $_{2}$ Pd $_{3}$ B and Li $_{2}$ Pt $_{3}$ B