title: Low-temperature dynamics of magnons in a spin-1/2 ladder compound.
abstract: We have used a combination of neutron resonant spin-echo and triple-axis spectroscopies to determine the energy, fine structure, and linewidth of the magnon resonance in the model spin-1/2 ladder antiferromagnet IPA-CuCl(3) at temperatures T≪Δ(0)/k(B), where Δ(0) is the spin gap at T=0. In this low-temperature regime we find that the results deviate substantially from the predictions of the nonlinear sigma model proposed as a description of magnon excitations in one-dimensional quantum magnets and attribute these deviations to real-space and spin-space anisotropies in the spin Hamiltonian as well as scattering of magnon excitations from a dilute density of impurities. These effects are generic to experimental realizations of one-dimensional quantum magnets.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Náfrádi
authors.forename: T
authors.initials: T
authors.lastname: Keller
authors.forename: H
authors.initials: H
authors.lastname: Manaka
authors.forename: A
authors.initials: A
authors.lastname: Zheludev
authors.forename: B
authors.initials: B
authors.lastname: Keimer