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TT: Fachverband Tiefe Temperaturen
TT 22: CE: Low-dimensional Systems - Materials 2
TT 22.7: Talk
Tuesday, March 15, 2011, 12:15–12:30, HSZ 304
Competing ground states in a novel Ni based hybrid S = 1 chain investigated with Electron spin resonance spectroscopy — •F. Lipps1, H. Maeter2, A. H. Arkenbout3, H. Luetkens4, G. Pascua4, Z. Shermadini4, T.T.M. Palstra3, H.-H. Klauss2, V. Kataev1, and B. Büchner1 — 1IFW Dresden, Germany — 2TU Dresden, Germany — 3Zernike Institute, University of Groningen, The Netherlands — 4PSI, Villigen, Switzerland
A new hybrid material that comprises arrays of one dimensional (1D) chains of NiCl6 octahedra separated by a framework of organic molecules is investigated with different methods. The Ni2+ (3d8) ions in the NiCl6 chain possess an integer spin S = 1. The temperature dependence of the static susceptibility shows a broad maximum suggesting an AFM coupling with a nearest neighbour exchange constant around 25 K. The ESR signal consists of a single lorentzian line at a g-factor of 2.2 typical for Ni2+. The ESR spectrum is isotropic proofing the absence of a single ion anisotropy. This indicates a good realization of the Haldane conjecture which predicts a non-magnetic ground state for an isotropic AFM Heisenberg S=1 chain and a gapped spin excitation spectrum. In contrast to this, a magnetic ordering is observed at temperatures below 10 K with ESR and µ sr. In the low temperature regime the static susceptibility and ESR measurements reveal an anisotropic behaviour for the magnetic field applied along and perpendicular to the chain. We discuss a possible ground state and spin dynamics of the studied compound.