title: Contrasting spin dynamics between underdoped and overdoped Ba(Fe1-xCox)2As2.
abstract: We report the first NMR investigation of spin dynamics in the overdoped nonsuperconducting regime of Ba(Fe1-xCox)2As2 up to x=0.26. We demonstrate that the absence of interband transitions with large momentum transfer Q{AF} approximately (pi/a,0) between the hole and electron Fermi surfaces results in complete suppression of antiferromagnetic spin fluctuations for x greater than or approximately 0.15. Our experimental results provide direct evidence for a correlation between T{c} and the strength of Q{AF} antiferromagnetic spin fluctuations.
authors.affiliation: Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S4M1, Canada.
authors.forename: F L
authors.initials: FL
authors.lastname: Ning
authors.forename: K
authors.initials: K
authors.lastname: Ahilan
authors.forename: T
authors.initials: T
authors.lastname: Imai
authors.forename: A S
authors.initials: AS
authors.lastname: Sefat
authors.forename: M A
authors.initials: MA
authors.lastname: McGuire
authors.forename: B C
authors.initials: BC
authors.lastname: Sales
authors.forename: D
authors.initials: D
authors.lastname: Mandrus
authors.forename: P
authors.initials: P
authors.lastname: Cheng
authors.forename: B
authors.initials: B
authors.lastname: Shen
authors.forename: H-H
authors.initials: HH
authors.lastname: Wen