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Structural Transitions and Magnetic Structure in NH4CuCl3 via 14N-NMR

Katsuaki Kodama·Masashi Takigawa·Yoshiyuki Shimaoka·Hidekazu Tanaka
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Abstract

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 $ν_{z}$ splits below 70 K, indicating a structural phase transition. At 4.2 K, eight N sites with distinct values of both $ν_{z}$ and the magnetic hyperfine shift $K_{z}$ 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.

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Katsuaki Kodama, Masashi Takigawa, Yoshiyuki Shimaoka, Hidekazu Tanaka. 2005-01-21. Structural Transitions and Magnetic Structure in NH4CuCl3 via 14N-NMR. https://doi.org/10.1143/ptps.159.228

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