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arXiv · 0709.2560

Nature of the spin dynamics and 1/3 magnetization plateau in azurite

K. C. Rule·A. U. B. Wolter·S. Süllow·D. A. Tennant·A. Brühl·S. Köhler·B. Wolf·M. Lang·J. Schreuer
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Abstract

We present a specific heat and inelastic neutron scattering study in magnetic fields up into the 1/3 magnetization plateau phase of the diamond chain compound azurite Cu$_3$(CO$_3$)$_2$(OH)$_2$. We establish that the magnetization plateau is a dimer-monomer state, {\it i.e.}, consisting of a chain of $S = 1/2$ monomers, which are separated by $S = 0$ dimers on the diamond chain backbone. The effective spin couplings $J_{mono}/k_B = 10.1(2)$ K and $J_{dimer}/k_B = 1.8(1)$ K are derived from the monomer and dimer dispersions. They are associated to microscopic couplings $J_1/k_B = 1(2)$ K, $J_2/k_B = 55(5)$ K and a ferromagnetic $J_3/k_B = -20(5)$ K, possibly as result of $d_{z^2}$ orbitals in the Cu-O bonds providing the superexchange pathways.

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K. C. Rule, A. U. B. Wolter, S. Süllow, D. A. Tennant, A. Brühl, S. Köhler, B. Wolf, M. Lang, J. Schreuer. 2007-09-17. Nature of the spin dynamics and 1/3 magnetization plateau in azurite. https://doi.org/10.1103/physrevlett.100.117202

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