Importance of the Fermi-surface topology to the superconducting state of the electron-doped pnictide Ba(Fe1-xCox) 2As2

Chang Liu, A. D. Palczewski, R. S. Dhaka, Takeshi Kondo, R. M. Fernandes, E. D. Mun, H. Hodovanets, A. N. Thaler, J. Schmalian, S. L. Bud'Ko, P. C. Canfield, A. Kaminski

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Abstract

We used angle-resolved photoemission spectroscopy and thermoelectric power to study the poorly explored, highly overdoped side of the phase diagram of Ba(Fe1-xCox)2As2 high-temperature superconductor. Our data demonstrate that several Lifshitz transitions- topological changes of the Fermi surface-occur for large x. The central hole barrel changes to ellipsoids that are centered at Z at x∼0.11 and subsequently disappear around x∼0.2; changes in thermoelectric power occur at similar x values. Tc decreases and goes to zero around x∼0.15-between the two Lifshitz transitions. Beyond x=0.2 the central pocket becomes electron-like and superconductivity does not exist. Our observations reveal the importance of the underlying Fermiology in electron-doped iron arsenides. We speculate that a likely necessary condition for superconductivity in these materials is the presence of the central hole pockets rather than nesting between central and corner pockets.

Original languageEnglish (US)
Article number020509
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number2
DOIs
StatePublished - Jul 25 2011

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