title: Quantum projection in an Ising spin liquid.
abstract: A transverse magnetic field is used to scan the diagonal and off-diagonal susceptibility of the uniaxial quantum magnet, LiHo(0.045) Y(0.955)F(4). Clusters of strongly coupled spins act as the primary source for the response functions, which result from a field-induced quantum projection of the system into a classically forbidden (meaning non-Ising) regime. Calculations based on spin pairs reproduce only some features of the data and fail to predict the measured off-diagonal response, providing evidence of a multispin collective state.
authors.affiliation: The James Franck Institute and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Silevitch
authors.forename: C M S
authors.initials: CM
authors.lastname: Gannarelli
authors.forename: A J
authors.initials: AJ
authors.lastname: Fisher
authors.forename: G
authors.initials: G
authors.lastname: Aeppli
authors.forename: T F
authors.initials: TF
authors.lastname: Rosenbaum