title: Structure of end states for a Haldane spin chain.
abstract: Inelastic neutron scattering was used to probe edge states in a quantum spin liquid. The experiment was performed on finite length antiferromagnetic spin-1 chains in Y2BaNi1-xMgxO5. At finite fields, there is a Zeeman resonance below the Haldane gap. The wave-vector dependence of its intensity provides direct evidence for staggered magnetization at chain ends, which decays exponentially towards the bulk [xi=8(1) at T=0.1 K]. Continuum contributions to the chain-end spectrum indicate interchain segment interactions. We also observe a finite size blueshift of the Haldane gap.
authors.affiliation: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kenzelmann
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: I A
authors.initials: IA
authors.lastname: Zaliznyak
authors.forename: C
authors.initials: C
authors.lastname: Broholm
authors.forename: J F
authors.initials: JF
authors.lastname: DiTusa
authors.forename: G
authors.initials: G
authors.lastname: Aeppli
authors.forename: T
authors.initials: T
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Oka
authors.forename: H
authors.initials: H
authors.lastname: Takagi