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Superconductivity of highly spin-polarized electrons in FeSe probed by $^{77}Se$ NMR

Molatta, S.; Opherden, D.; Wosnitza, J.; Opherden, L.; Zhang, Z. T.; Wolf, T. 1; Löhneysen, H. v. 1; Sarkar, R.; Biswas, P. K.; Grafe, H.-J.; Kühne, H.
1 Institut für QuantenMaterialien und Technologien (IQMT), Karlsruher Institut für Technologie (KIT)

Abstract (englisch):

A number of recent experiments indicate that the iron-chalcogenide FeSe provides the long-sought possibility to study bulk superconductivity in the cross-over regime between the weakly coupled Bardeen-Cooper-Schrieffer (BCS) pairing and the strongly coupled Bose-Einstein condensation (BEC). We report on $^{77}Se$ nuclear magnetic resonance experiments of FeSe, focused on the superconducting phase for strong magnetic fields applied along the c axis, where a distinct state with large spin polarization was reported. We determine this high-field state as bulk superconducting with high spatial homogeneity of the low-energy spin fluctuations. Further, we find that the static spin susceptibility becomes unusually small at temperatures approaching the superconducting state, despite the presence of pronounced spin fluctuations. Taken together, our results clearly indicate that FeSe indeed features an unusual field-induced superconducting state of a highly spin-polarized Fermi liquid in the BCS-BEC crossover regime.

DOI: 10.1103/PhysRevB.104.014504
Zitationen: 4
Web of Science
Zitationen: 4
Zitationen: 7
Zugehörige Institution(en) am KIT Institut für QuantenMaterialien und Technologien (IQMT)
Physikalisches Institut (PHI)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 07.2021
Sprache Englisch
Identifikator ISSN: 2469-9950, 2469-9969
KITopen-ID: 1000136068
HGF-Programm 47.11.01 (POF IV, LK 01) Topological Matter
Erschienen in Physical Review B
Verlag American Physical Society (APS)
Band 104
Heft 1
Seiten Art.-Nr. 014504
Vorab online veröffentlicht am 12.07.2021
Nachgewiesen in Dimensions
Web of Science
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