Low frequency spin dynamics in the quantum magnet copper pyrazine dinitrate

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.

5 pages, 6 figures, published in Physica Status Solidi B

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Cited by in corpus (3)

• Field and temperature dependence of the NMR relaxation rate in the magnetic quadrupolar liquid phase of spin-1/2 frustrated ferromagnetic chains
• Dynamics of a Heisenberg spin chain in the quantum critical regime: NMR experiment versus effective field theory
• Exchange constants in molecule-based magnets derived from density functional methods