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Screening of pair fluctuations in superconductors with coupled shallow and deep bands: A route to higher-temperature superconductivity

L. Salasnich, A. A. Shanenko, A. Vagov, J. Albino Aguiar, A. Perali

DOI 10.1103/PhysRevB.100.064510 · Physical Review B

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Abstract

A combination of strong Cooper pairing and weak superconducting fluctuations is crucial to achieve and stabilize high-Tc superconductivity. We demonstrate that a coexistence of a shallow carrier band with strong pairing and a deep band with weak pairing, together with the Josephson-like pair transfer between the bands to couple the two condensates, realizes an optimal multicomponent superconductivity regime: it preserves strong pairing to generate large gaps and a very high critical temperature but screens the detrimental superconducting fluctuations, thereby suppressing the pseudogap state. Surprisingly, we find that the screening is very efficient even when the interband coupling is very small. Thus, a multiband superconductor with a coherent mixture of condensates in the BCS regime (deep band) and in the BCS-BEC crossover regime (shallow band) offers a promising route to higher critical temperatures.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
LiFe1-xCoxAs

Archive — visibility unverified

Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

15Pressure not reportedunknown
LiFe1-xCoxAs

Archive — visibility unverified

Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

18Pressure not reportedunknown

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