Abstract
We theoretically show that a two-band system with very different masses harbors a resonant pair scattering that leads to novel pairing properties, as highlighted by the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) crossover. Most importantly, the interband pair-exchange coupling induces an effective intraband attraction in each band, enhancing the superfluidity/superconductivity. The effect, a kind of Suhl-Kondo mechanism, is specifically enhanced when the second band has a heavy mass and is incipient (lying close to, but just above, the chemical potential, $\mu$), which we call a resonant pair scattering. By elucidating the dependence of the effective interactions and gap functions on $\mu$, we can draw an analogy between the resonant pair scattering and the Feshbach resonance.
Highlights
One of the central issues in superconductivity/ superfluidity is the crossover between the Bardeen-CooperSchrieffer (BCS) and Bose-Einstein condensation (BEC) regimes, or a crossover between weak- and strong-coupling regimes [1,2,3,4]
We theoretically show that a two-band system with very different masses harbors a resonant pair scattering that leads to novel pairing properties, as highlighted by the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) crossover
In two-band systems the gap function has two components, and we solve the two-component gap equation where we focus on the intraband pairing in the case in which the chemical potential is set around the bottom of the incipient band
Summary
One of the central issues in superconductivity/ superfluidity is the crossover between the Bardeen-CooperSchrieffer (BCS) and Bose-Einstein condensation (BEC) regimes, or a crossover between weak- and strong-coupling regimes [1,2,3,4] Another crucial interest in recent years is the multiband superconductors and superfluids, which harbor many specific interests. In cold-atom systems, there exists, in addition to the magnetic Feshbach resonance, what is called the “orbital Feshbach resonance” when the atomic spieces (such as Yb) have inert electron spins but multiple orbital states. This can be utilized to provide with open and closed channels to realize the unitarity-limit region
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
