Why Does Undoped FeSe Become A High Tc Superconductor Under Pressure?

Abstract

Unlike the parent phases of the iron-arsenide high Tc superconductors, undoped FeSe is not magnetically ordered and exhibits superconductivity with Tc~9K. Equally surprising is the fact that applied pressure dramatically enhances the modest Tc to ~37K. We investigate the electronic properties of FeSe using 77Se NMR to search for the key to the superconducting mechanism. We demonstrate that the electronic properties of FeSe are very similar to those of electron-doped FeAs superconductors, and that antiferromagnetic spin fluctuations are strongly enhanced near Tc. Furthermore, applied pressure enhances spin fluctuations. Our findings suggest a link between spin fluctuations and the superconducting mechanism in FeSe.

Accepted for publication in Phys. Rev. Lett. after minor revision

References in corpus (6)

• Spin density wave anomaly at 140 K in the ternary iron arsenide BaFe2As2
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• Superconductivity at 27 K in tetragonal FeSe under high pressure
• Commensurate Itinerant Antiferromagnetism in BaFe2As2: 75As-NMR Studies on a Self-Flux Grown Single Crystal
• 19-F NMR Investigation of Iron-pnictide Superconductor LaFeAsO(0.89)F(0.11)
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Cited by in corpus (6)

• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Metal - Insulator transition in Fe1.01-xCuxSe
• NMR investigation of superconductivity and antiferromagnetism in CaFe${}_2$As${}_2$ under pressure
• The Electronic Phase Diagram of the Iron-based High Tc Superconductor Ba(Fe(1-x)Co(x))2As2 Under Hydrostatic Pressure (0 < x <0.099)
• The local atomic structure of superconducting Fe-Se-Te