Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

TT: Fachverband Tiefe Temperaturen

TT 22: CE: Low-dimensional Systems - Materials 2

TT 22.7: Vortrag

Dienstag, 15. März 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.