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arXiv · 0901.0859

Spin Configuration in the 1/3 Magnetization Plateau of Azurite Determined by NMR

F. Aimo·S. Kramer·M. Klanjsek·M. Horvatic·C. Berthier·H. Kikuchi
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Abstract

High magnetic field $^{63,65}$Cu NMR spectra were used to determine the local spin polarization in the 1/3 magnetization plateau of azurite, Cu$_3$(CO$_3$)$_2$(OH)$_2$, which is a model system for the distorted diamond antiferromagnetic spin-1/2 chain. The spin part of the hyperfine field of the Cu2 (dimer) sites is found to be field independent, negative and strongly anisotropic, corresponding to $\approx$10 % of fully polarized spin in a $d$-orbital. This is close to the expected configuration of the "quantum" plateau, where a singlet state is stabilized on the dimer. However, the observed non-zero spin polarization points to some triplet admixture, induced by strong asymmetry of the diamond bonds $J_1$ and $J_3$.

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F. Aimo, S. Kramer, M. Klanjsek, M. Horvatic, C. Berthier, H. Kikuchi. 2009-02-25. Spin Configuration in the 1/3 Magnetization Plateau of Azurite Determined by NMR. https://doi.org/10.1103/physrevlett.102.127205

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