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BCS-BEC crossover induced by a shallow band: Pushing standard superconductivity types apart

BCS-BEC crossover induced by a shallow band: Pushing standard superconductivity types apart

Authors :
Andrea Perali
J. Albino Aguiar
A. A. Shanenko
Sebastian Wolf
Alexei Vagov
Vollrath M. Axt
Source :
Physical Review B. 95
Publication Year :
2017
Publisher :
American Physical Society (APS), 2017.

Abstract

The appearance of a shallow band(s) drives a superconductor towards the BCS-BEC crossover, conventionally associated with notable changes in single-particle properties and an elevated critical temperature. Here we demonstrate that the proximity to the crossover induced by a shallow band has also a dramatic effect on the phase diagram of the superconducting magnetic properties. When the system passes from the BCS to BEC regime, the intertype domain between superconductivity types I and II enlarges systematically, being inversely proportional to the square of the Cooper-pair radius, the main parameter that controls the BCS-BEC superconductivity. We also show that despite the presence of a shallow band, the condensate fluctuations are suppressed when it coexists in one material with standard deep bands, as in recent iron chalcogenides ${\mathrm{Fe}\mathrm{Se}}_{x}{\mathrm{Te}}_{1\ensuremath{-}x}$ and $\mathrm{FeSe}$.

Details

ISSN :
24699969 and 24699950
Volume :
95
Database :
OpenAIRE
Journal :
Physical Review B
Accession number :
edsair.doi.dedup.....a224f011123b5196ae9b170a32a5c36f
Full Text :
https://doi.org/10.1103/physrevb.95.094521