Ab initio study of orbital-selective superconductivity in γ-BiPd

Sonu Prasad Keshri; Guang-Yu Guo

doi:10.1103/3l59-8g35

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Ab initio study of orbital-selective superconductivity in γ-BiPd

Sonu Prasad Keshri, Guang-Yu Guo

DOI 10.1103/3l59-8g35 · Physical Review B

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Abstract

We investigate the superconducting (SC) properties of experimentally realized γ-BiPd by solving the anisotropic Migdal-Eliashberg equations in conjunction with ab initio relativistic calculations of the electron and phonon band structures as well as electron-phonon coupling (EPC) matrix elements. Our study reveals that γ-BiPd possesses a complex Fermi surface (FS), consisting of two electron pockets and one hole pocket, each characterized by distinct atomic orbitals. Our key finding is that the superconductivity in γ-BiPd is primarily orbital selective, arising from Bi p orbitals, and distributed anisotropically on the FS, although contribution from Pd d orbitals, particularly on the hole pocket, is also discernible. While our results show an anisotropic nature of the k-dependent SC gap Δk and EPC strength λk across the FS, calculated superconducting quasiparticle density of states NS spectra exhibit a U-shaped gap and Δk distribution forms a single peak, being consistent with the spin-singlet s-wave superconductivity observed in this material. The calculated Tc is ∼2.0K, agreeing in order of magnitude with the experimental value of 3.3 K in γ-BiPd thin films. The predicted EPC-enhanced Sommerfeld coefficient γn of 0.141mJ/K2cm3 is similar to the experimental γn value (0.119mJ/K2cm3) of the isoelectronic and isostructural Bi(Pd0.5Pt0.5) alloy.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
BiPd Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2	Pressure not reported	unknown
BiPd Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.3	Pressure not reported	unknown
BiPd Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.7	Pressure not reported	unknown
Bi2Pd Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.6	Pressure not reported	unknown