Electron-phonon superconductivity in LaNiPO

We report first-principles calculations of the electronic structure, phonon dispersions, and electron-phonon coupling of LaNiPO. These calculations show that this material can be explained as a conventional electron-phonon superconductor in contrast to the FeAs based high-temperature superconductors.

Figure 1

Calculated LDA band structure of LaNiPO using the experimental lattice parameters and relaxed internal coordinates, $z_{\text{La}}=0.1506$ and $z_{\text{P}}=0.6210$.

Figure 2

(Color online) Calculated LDA density of states of LaNiPO on a per formula unit both spins basis. The projections are onto the LAPW spheres.

Figure 3

(Color online) Calculated LDA density of states of LaFePO on a per formula unit both spins basis. The projections are onto the LAPW spheres. The Fe sphere radius was $2.1a_0$, which is equal to the Ni sphere radius used in Fig. 2. This calculation was done for the experimental lattice parameters,[26] and relaxed internal coordinates, $z_{\text{P}}=0.6201$, $z_{\text{La}}=0.1484$.

Figure 4

(Color online) Calculated LDA Fermi surface of LaNiPO shaded by velocity. The top panel shows a view along the tetragonal axis while the bottom panel shows a tilted view.

Figure 5

Calculated phonon dispersions of LaNiPO as obtained within linear response.

Figure 6

Calculated phonon density of states, $G\left(\omega \right)$, and electron-phonon spectral functional ${\alpha }^{2}F\left(\omega \right)$.