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 13C-NMR spectroscopy. Measurements of the nuclear spin-lattice relaxation rate T1−1 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 T1−1-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.
@article{arxiv.1003.4535,
title = {Low frequency spin dynamics in the quantum magnet copper pyrazine dinitrate},
author = {H. Kuehne and M. Guenther and S. Grossjohann and W. Brenig and F. J. Litterst and A. P. Reyes and P. L. Kuhns and M. M. Turnbull and C. P. Landee and H. -H. Klauss},
journal= {arXiv preprint arXiv:1003.4535},
year = {2010}
}
Comments
5 pages, 6 figures, published in Physica Status Solidi B