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arXiv · 1003.4535

Low frequency spin dynamics in the quantum magnet copper pyrazine dinitrate

H. Kuehne·M. Guenther·S. Grossjohann·W. Brenig·F. J. Litterst·A. P. Reyes·P. L. Kuhns·M. M. Turnbull·C. P. Landee·H. -H. Klauss
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Abstract

The S=1/2 antiferromagnetic Heisenberg chain exhibits a magnetic field driven quantum critical point. We study the low frequency spin dynamics in copper pyrazine dinitrate (CuPzN), a realization of this model system of quantum magnetism, by means of $^{13}$C-NMR spectroscopy. Measurements of the nuclear spin-lattice relaxation rate $T_1^{-1}$ in the vicinity of the saturation field are compared with quantum Monte Carlo calculations of the dynamic structure factor. Both show a strong divergence of low energy excitations at temperatures in the quantum regime. The analysis of the anisotropic $T_1^{-1}$-rates and frequency shifts allows one to disentangle the contributions from transverse and longitudinal spin fluctuations for a selective study and to determine the transfer of delocalized spin moments from copper to the neighboring nitrogen atoms.

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H. Kuehne, M. Guenther, S. Grossjohann, W. Brenig, F. J. Litterst, A. P. Reyes, P. L. Kuhns, M. M. Turnbull, C. P. Landee, H. -H. Klauss. 2010-03-23. Low frequency spin dynamics in the quantum magnet copper pyrazine dinitrate. https://doi.org/10.1002/pssb.200983077

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