Article Dans Une Revue Physical Review Letters Année : 2004

$\mu$SR study of the quantum dynamics in the frustrated $S=\frac{3}{2}$ kagomé bilayers

Résumé

We present $\mu$SR experiments in the $S=\frac{3}{2}$ kagomé bilayer compound Ba$_{2}$Sn$_{2}$ZnGa$_{10-7p}$Cr$_{7p}$O$_{22}$ (BSZCGO$(p)$) and compare it to the isostructural SrCr$_{9p}$Ga$_{12-9p}$O$_{19}$ (SCGO$(p)$), including for the latter new results for $p\geq0.89$. Quantum-dynamical low energy magnetic excitations are evidenced in this novel compound. We study the evolution of the muon relaxation rate with $p$, $T$ and field. A phenomenological model for the muon relaxation based on sporadic dynamics due to spin excitations in a singlet sea proposed by Uemura \emph{et al.} [Phys. Rev. Lett. \textbf{73}, 3306 (1994)]. is extended to all fields and $T$-range. Its connexion to the RVB picture is discussed, and we argue that such coherent states might mediate the interactions between "impurities" which induce the spin glass freezing.

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Dates et versions

hal-00002813 , version 1 (10-09-2004)
hal-00002813 , version 2 (13-09-2004)

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David Bono, P. Mendels, G. Collin, N. Blanchard, F. Bert, et al.. $\mu$SR study of the quantum dynamics in the frustrated $S=\frac{3}{2}$ kagomé bilayers. Physical Review Letters, 2004, 93, pp.187201. ⟨10.1103/PhysRevLett.93.187201⟩. ⟨hal-00002813v2⟩
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