title: Longitudinal and transverse Zeeman ladders in the Ising-like chain antiferromagnet BaCo(2)V(2)O(8).
abstract: We explore the spin dynamics emerging from the Néel phase of the chain compound antiferromagnet BaCo(2)V(2)O(8). Our inelastic neutron scattering study reveals unconventional discrete spin excitations, so-called Zeeman ladders, understood in terms of spinon confinement, due to the interchain attractive linear potential. These excitations consist of two interlaced series of modes, respectively, with transverse and longitudinal polarization. The latter, which correspond to a longitudinal fluctuation of the ordered moment, have no classical counterpart and are related to the zero-point fluctuations that weaken the ordered moment in weakly coupled quantum chains. Our analysis reveals that BaCo(2)V(2)O(8), with moderate Ising anisotropy and sizable interchain interactions, remarkably fulfills the conditions necessary for the observation of discrete long-lived longitudinal excitations.
authors.affiliation: Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble, France and CEA, INAC-SPSMS, F-38000 Grenoble, France.
authors.forename: B
authors.initials: B
authors.lastname: Grenier
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, CEA-Saclay, F-91191 Gif-sur-Yvette, France.
authors.forename: S
authors.initials: S
authors.lastname: Petit
authors.affiliation: CNRS, Institut Néel, F-38042 Grenoble, France and Université Grenoble Alpes, Institut Néel, F-38042 Grenoble, France.
authors.forename: V
authors.initials: V
authors.lastname: Simonet
authors.affiliation: Institut Laue-Langevin, CS 20156, F-38042 Grenoble Cedex 9, France.
authors.forename: E
authors.initials: E
authors.lastname: Canévet
authors.affiliation: Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble, France and CEA, INAC-SPSMS, F-38000 Grenoble, France.
authors.forename: L-P
authors.initials: LP
authors.lastname: Regnault
authors.affiliation: Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble, France and CEA, INAC-SPSMS, F-38000 Grenoble, France.
authors.forename: S
authors.initials: S
authors.lastname: Raymond
authors.affiliation: CNRS, Institut Néel, F-38042 Grenoble, France and Université Grenoble Alpes, Institut Néel, F-38042 Grenoble, France.
authors.forename: B
authors.initials: B
authors.lastname: Canals
authors.affiliation: Université Grenoble Alpes, Laboratoire National des Champs Magnétiques Intenses, F-38000 Grenoble, France and CNRS, Laboratoire National des Champs Magnétiques Intenses, F-38000 Grenoble, France.
authors.forename: C
authors.initials: C
authors.lastname: Berthier
authors.affiliation: CNRS, Institut Néel, F-38042 Grenoble, France and Université Grenoble Alpes, Institut Néel, F-38042 Grenoble, France.
authors.forename: P
authors.initials: P
authors.lastname: Lejay