title: From incommensurate correlations to mesoscopic spin resonance in YbRh2Si2.
abstract: Spin fluctuations are reported near the magnetic field-driven quantum critical point in YbRh(2)Si(2). On cooling, ferromagnetic fluctuations evolve into incommensurate correlations located at q(0) = ±(δ,δ), with δ = 0.14 ± 0.04 r.l.u. At low temperatures, an in-plane magnetic field induces a sharp intradoublet resonant excitation at an energy E(0) = gμ(B)μ(0)H with g = 3.8 ± 0.2. The intensity is localized at the zone center, indicating precession of spin density extending ξ = 6 ± 2 Å beyond the 4f site.
authors.affiliation: NIST Center for Neutron Research, Gaithersburg, Maryland 20899, USA.
authors.forename: C
authors.initials: C
authors.lastname: Stock
authors.forename: C
authors.initials: C
authors.lastname: Broholm
authors.forename: F
authors.initials: F
authors.lastname: Demmel
authors.forename: J
authors.initials: J
authors.lastname: Van Duijn
authors.forename: J W
authors.initials: JW
authors.lastname: Taylor
authors.forename: H J
authors.initials: HJ
authors.lastname: Kang
authors.forename: R
authors.initials: R
authors.lastname: Hu
authors.forename: C
authors.initials: C
authors.lastname: Petrovic