title: Hierarchy of bound states in the one-dimensional ferromagnetic Ising chain CoNb2O6 investigated by high-resolution time-domain terahertz spectroscopy.
abstract: Kink bound states in the one-dimensional ferromagnetic Ising chain compound CoNb2O6 have been studied using high-resolution time-domain terahertz spectroscopy in zero applied magnetic field. When magnetic order develops at low temperature, nine bound states of kinks become visible. Their energies can be modeled exceedingly well by the Airy function solutions to a 1D Schrödinger equation with a linear confining potential. This sequence of bound states terminates at a threshold energy near 2 times the energy of the lowest bound state. Above this energy scale we observe a broad feature consistent with the onset of the two particle continuum. At energies just below this threshold we observe a prominent excitation that we interpret as a novel bound state of bound states--two pairs of kinks on neighboring chains.
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Morris
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Center for Integrated Nanotechnologies, Los Alamos National Laboratory. MS K771. Los Alamos, New Mexico 87545, USA.
authors.forename: R
authors.initials: R
authors.lastname: Valdés Aguilar
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: A
authors.initials: A
authors.lastname: Ghosh
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Koohpayeh
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: J
authors.initials: J
authors.lastname: Krizan
authors.affiliation: Department of Chemistry, Princeton University, Princeton, New Jersey 08544, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Cava
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: O
authors.initials: O
authors.lastname: Tchernyshyov
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA and Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: McQueen
authors.affiliation: The Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: N P
authors.initials: NP
authors.lastname: Armitage