We report results of 14N-NMR experiments on NH4CuCl3 at the magnetic field of 7 T, where the 1/4-magnetization plateau is observed at low temperatures. The quadrupole splitting parameter νz splits below 70 K, indicating a structural phase transition. At 4.2 K, eight N sites with distinct values of both νz and the magnetic hyperfine shift Kz are resolved in the NMR spectrum for general field directions. We then conlude that the magnetic structure in the 1/4-plateau does not break the symmetry of the crystal. Based on the NMR and the recent neutron scattering results by Ruegg et al. [Phys. Rev. Lett. 93 (2004) 037207], we propose that triplet dimers in the 1/4-plateau is formed not between the nearest neighbor pairs but over different chains.
@article{arxiv.cond-mat/0501451,
title = {Structural Transitions and Magnetic Structure in NH4CuCl3 via 14N-NMR},
author = {Katsuaki Kodama and Masashi Takigawa and Yoshiyuki Shimaoka and Hidekazu Tanaka},
journal= {arXiv preprint arXiv:cond-mat/0501451},
year = {2015}
}
Comments
7 pages, 5 figures, Proceedings for the International Symposium on Quantum Spin Systems, submitted to Prog. Theor. Phys. Author change