Cooper pairing, flat-band superconductivity, and quantum geometry in the pyrochlore-Hubbard model

M. Iskin

doi:10.1103/PhysRevB.109.174508

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Cooper pairing, flat-band superconductivity, and quantum geometry in the pyrochlore-Hubbard model

M. Iskin

DOI 10.1103/PhysRevB.109.174508 · Physical Review B

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Abstract

We investigate the impacts of the quantum geometry of Bloch states, specifically through the band-resolved quantum-metric tensor, on Cooper pairing and flat-band superconductivity in a three-dimensional pyrochlore-Hubbard model. First we analyze the low-lying two-body spectrum exactly, and show that the pairing order parameter is uniform in this four-band lattice. This allows us to establish direct relations between the superfluid weight of a multiband superconductor and (i) the effective mass of the lowest-lying two-body branch at zero temperature, (ii) the kinetic coefficient of the Ginzburg-Landau theory in proximity to the critical temperature, and (iii) the velocity of the low-energy Goldstone modes at zero temperature. Furthermore, we perform a comprehensive numerical analysis of the superfluid weight and Goldstone modes, exploring both their conventional and geometric components at zero temperature.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
CaNi2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
CeRu2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown