Regensburg 2004 – wissenschaftliches Programm
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MA: Magnetismus
MA 21: Bio- und molekularer Magnetismus
MA 21.2: Vortrag
Donnerstag, 11. März 2004, 10:30–10:45, H22
High-field magnetization study of the S = 1/2 antiferromagnetic Heisenberg chain [PM Cu(NO3)2(H2O)2]n with field-induced gap — •S. Süllow1, A.U.B. Wolter1, H. Rakoto2, M. Costes2, A. Honecker3, W. Brenig3, A. Klümper4, H.-H. Klauss1, F.J. Litterst1, R. Feyerherm5, and D. Jérome6 — 1IMNF, TU Braunschweig, Braunschweig — 2Laboratoire National des Champs Magnétique Pulsés, Toulouse, France — 3ITP, TU Braunschweig, Braunschweig, — 4FB Physik, Bergische Universität Wuppertal, Wuppertal — 5HMI GmbH, Berlin — 6Université Paris-Sud, Orsay
We present a high-field magnetization study of the S=1/2 antiferromagnetic Heisenberg chain [PM Cu(NO3)2(H2O)2]n. For this material, as result of the Dzyaloshinskii-Moriya interaction and a staggered g-tensor, the ground state is characterized by an anisotropic field induced spin excitation gap and a staggered magnetization. Our data reveal the qualitatively different behaviour in the directions of maximum and zero spin excitation gap. The data are analyzed via exact diagonalization of a linear spin chain with up to 20 sites and on basis of the Bethe ansatz equations, respectively. For both directions we find very good agreement between experimental data and theoretical calculations. We extract the magnetic coupling strength J/kB along the chain directions to 36.3(5) K and determine the field dependence of the staggered magnetization component ms. This work has partially been supported by funds of the European contract no. HPRI-CT-1999-40013 and by the DFG under contract no. SU229/6-1.