Anton Potočnik
Size and symmetry of the superconducting gap in the f.c.c. Cs3C60 polymorph close to the metal-Mott insulator boundary
Potočnik, Anton; Krajnc, Andraž; Jeglič, Peter; Takabayashi, Yasuhiro; Ganin, Alexey Y.; Prassides, Kosmas; Rosseinsky, Matthew J.; Arčon, Denis
Authors
Andraž Krajnc
Peter Jeglič
Yasuhiro Takabayashi
Alexey Y. Ganin
Kosmas Prassides
Matthew J. Rosseinsky
Denis Arčon
Abstract
The alkali fullerides, A3C60 (A = alkali metal) are molecular superconductors that undergo a transition to a magnetic Mott-insulating state at large lattice parameters. However, although the size and the symmetry of the superconducting gap, Δ, are both crucial for the understanding of the pairing mechanism, they are currently unknown for superconducting fullerides close to the correlation-driven magnetic insulator. Here we report a comprehensive nuclear magnetic resonance (NMR) study of face-centred-cubic (f.c.c.) Cs3C60 polymorph, which can be tuned continuously through the bandwidth-controlled Mott insulator-metal/superconductor transition by pressure. When superconductivity emerges from the insulating state at large interfullerene separations upon compression, we observe an isotropic (s-wave) Δ with a large gap-to-superconducting transition temperature ratio, 2Δ0/kBTc = 5.3(2) [Δ0 = Δ(0 K)]. 2Δ0/kBTc decreases continuously upon pressurization until it approaches a value of ~3.5, characteristic of weak-coupling BCS theory of superconductivity despite the dome-shaped dependence of Tc on interfullerene separation. The results indicate the importance of the electronic correlations for the pairing interaction as the metal/superconductor-insulator boundary is approached.
Citation
Potočnik, A., Krajnc, ., Jeglič, ., Takabayashi, Y., Ganin, A. Y., Prassides, K., …Arčon, D. (2014). Size and symmetry of the superconducting gap in the f.c.c. Cs3C60 polymorph close to the metal-Mott insulator boundary. Scientific Reports, 4, Article 4265. https://doi.org/10.1038/srep04265
Journal Article Type | Article |
---|---|
Publication Date | Mar 3, 2014 |
Deposit Date | May 21, 2014 |
Publicly Available Date | Oct 22, 2014 |
Journal | Scientific Reports |
Publisher | Nature Research |
Peer Reviewed | Peer Reviewed |
Volume | 4 |
Article Number | 4265 |
DOI | https://doi.org/10.1038/srep04265 |
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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/3.0/
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