ARPES BCS-BEC Crossover Transition – Fe(1+x)Se(x)Te(1-x)

by Tommy on 17/05/2017

Grok and you shall know.

Tuning across the BCS-BEC crossover in the multiband superconductor Fe1+ySexTe1−x : An angle-resolved photoemission study, S. Rinott, K.B. Chashka A. Ribak, E. D. L. Rienks A. Taleb-Ibrahimi, P. Le Fevre, F.Bertran, M. Randeria and A.Kanigel, Science Advances 3, 4, e1602372 (21 April 2017), doi:101126/sciadv.1602372

The crossover from Bardeen-Cooper-Schrieffer (BCS) superconductivity to Bose-Einstein condensation (BEC) is difficult to realize in quantum materials because, unlike in ultracold atoms, one cannot tune the pairing interaction. We realize the BCS-BEC crossover in a nearly compensated semimetal Fe1+ySexTe1−x by tuning the Fermi energy, ϵF, via chemical doping, which permits us to systematically change Δ/ϵF from 0.16 to 0.5 were Δ is the superconducting (SC) gap. We use angle-resolved photoemission spectroscopy to measure the Fermi energy, the SC gap and characteristic changes in the SC state electronic dispersion as the system evolves from a BCS to a BEC regime. Our results raise important questions about the crossover in multiband superconductors which go beyond those addressed in the context of cold atoms.

This is how it will be done from now on.

Got any other ideas? I can think of a few.

I completely failed to predict this in 1994.

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