Campus Units

Physics and Astronomy, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

5-1-2014

Journal or Book Title

Physical Review B

Volume

89

Issue

18

First Page

180503(R)

DOI

10.1103/PhysRevB.89.180503

Abstract

Using inelastic neutron scattering, we show that the onset of superconductivity in underdoped Ba(Fe1−xCox)2As2 coincides with a crossover from well-defined spin waves to overdamped and diffusive spin excitations. This crossover occurs despite the presence of long-range stripe antiferromagnetic order for samples in a compositional range from x=0.04 to 0.055, and is a consequence of the shrinking spin-density wave gap and a corresponding increase in the particle-hole (Landau) damping. The latter effect is captured by a simple itinerant model relating Co doping to changes in the hot spots of the Fermi surface. We argue that the overdamped spin fluctuations provide a pairing mechanism for superconductivity in these materials.

Comments

This article is published as Tucker, G. S., R. M. Fernandes, D. K. Pratt, A. Thaler, N. Ni, K. Marty, Andrew D. Christianson, M. D. Lumsden, B. C. Sales, A. S. Sefat, S. L. Bud’ko, P. C. Canfield, A. Kreyssig, A. I. Goldman, and R. J. McQueeney. "Crossover from spin waves to diffusive spin excitations in underdoped Ba (Fe 1− x Co x) 2 As 2." Physical Review B 89, no. 18 (2014): 180503. DOI: 10.1103/PhysRevB.89.180503. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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