Tuning across the BCS-BEC crossover in the multiband superconductor Fe1+ySexTe1−x: An angle-resolved photoemission study

Shahar Rinott, K. B. Chashka, Amit Ribak, Emile D.L. Rienks, Amina Taleb-Ibrahimi, Patrick Le Fevre, François Bertran, Mohit Randeria, Amit Kanigel

Research output: Contribution to journalArticlepeer-review

Abstract

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 eF via chemical doping, which permits us to systematically change D/eF from 0.16 to 0.50, where D 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.

Original languageEnglish
Article numbere1602372
JournalScience Advances
Volume3
Issue number4
DOIs
StatePublished - Apr 2017

All Science Journal Classification (ASJC) codes

  • General

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