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Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 13: Correlated Electrons: Low-dimensional Systems - Materials 1

TT 13.5: Talk

Tuesday, February 26, 2008, 10:30–10:45, H 2053

Spin dynamics in the plateau phase of the 1D distorted diamond chain azurite, Cu3(CO3)2(OH)2Kirrily Rule1, Anja Wolter1, •Stefan Süllow2, Bernd Wolf3, Michael Lang3, Jürgen Schreuer4, and Alan Tennant11BENSC, HMI, 14109 Berlin — 2IPKM, TU Braunschweig, 38106 Braunschweig — 3Physikalisches Institut, J.W. Goethe-Universität Frankfurt, 60438 Frankfurt(M) — 4Ruhr-Universität Bochum, Bochum

Recently, azurite, Cu3(CO3)2(OH)2, has been described as an ideal example of a frustrated one-dimensional (1D) diamond-chain antiferromagnet [1]. A 1/3 magnetisation plateau has been observed in azurite for fields between 11 and 30T applied perpendicular to both the crystallographic b axis and Cu2+ chain direction. Here, we present a study by means of inelastic neutron scattering, which has been performed on a large single crystal of azurite in fields up to 14T applied perpendicular to the chain direction, viz. in the plateau phase. Our data in the plateau phase indicate that the magnetic excitations can be described by a dimer-monomer model with two distinct energy scales. The dispersion function of the monomer chain reveals an effective spin coupling of Jeff = 10.1(2) K, while the lowest Zeeman-split dimer branch has an effective dimer-dimer coupling of Jdimer = 1.8(1) K. We will discuss possible values for the exchange constants J1, J2 and J3 of the diamond chain model to account for these observations, based on a perturbative approach.

[1] H. Kikuchi et al. Phys. Rev. Lett. 94 (2005) 227201

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