Regensburg 2010 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 27: CE: Poster Session
TT 27.74: Poster
Wednesday, March 24, 2010, 14:00–18:00, Poster D1
Electron spin resonance spectroscopy of a novel Ni based hybrid S = 1 chain — •F. Lipps1, A. H. Arkenbout2, A. Meetsma2, T. T. M. Palstra2, P. H. M. van Loosdrecht2, V. Kataev1, and B. Büchner1 — 1IFW Dresden, Institute for Solid State Research, Dresden, Germany — 2Zernike Institute for Advanced Materials, University of Groningen, The Netherlands
We present results of a multifrequency ESR and static magnetization study of single crystals of a new hybrid material that comprises arrays of one dimensional (1D) chains of NiCl6 octahedra separated by a framework of organic molecules. The Ni2+ (3d8) ions in the NiCl6 chain possess an integer spin S = 1. Thus, in case of the antiferromagnetic (AFM) coupling, such a chain may provide an experimental realization of a prominent 1D S=1 Heisenberg model, the Haldane chain. In contrast to the S=1/2 chain it has a nonmagnetic ground state and a gapped spectrum of spin excitations. The ESR response of the studied samples is characterized by a single well-defined lorentzian line with a g-factor of g≃ 2.2. The T-dependence of the ESR intensity which is proportional to the static spin susceptibility as well as the bulk static magnetization reveal a low temperature maximum suggesting an AFM coupling of the order of ∼ 24 K. In this low temperature regime the ESR signal broadens substantially which indicates a growth of the low-frequency AFM dynamic spin correlations. Remarkably, no indications of the development of the static local internal fields due to the long-range order are observed in the ESR spectra. We discuss a possible ground state and spin dynamics of the studied compound.