Bono D, Mendels P, Collin G, Blanchard N, Bert F, Amato A, Baines C, Hillier A D
Laboratoire de Physique des Solides, UMR 8502, Université Paris-Sud, 91405 Orsay, France.
Phys Rev Lett. 2004 Oct 29;93(18):187201. doi: 10.1103/PhysRevLett.93.187201. Epub 2004 Oct 26.
We present muSR experiments in the S=3/2 kagomé bilayer compound Ba(2)Sn(2)ZnGa(10-7p)Cr(7p)O22 [BSZCGO(p)] and compare it to the isostructural SrCr(9p)Ga(12-9p)O19 [SCGO(p)], including for the latter new results for p > or =0.89. 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 et al. is extended to all fields and T range. Its connection 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.
我们展示了在S = 3/2的 kagomé 双层化合物Ba₂Sn₂ZnGa₁₀₋₇ₚCr₇ₚO₂₂ [BSZCGO(p)] 中的μ子自旋旋转（muSR）实验，并将其与同结构的SrCr₉ₚGa₁₂₋₉ₚO₁₉ [SCGO(p)] 进行比较，其中包括后者在p≥0.89时的新结果。在这种新型化合物中证实了量子动力学低能磁激发。我们研究了μ子弛豫率随p、T和磁场的变化。上村等人提出的基于单重态海中自旋激发导致的零星动力学的μ子弛豫唯象模型被扩展到所有磁场和温度范围。讨论了它与共振价键（RVB）图像的联系，并且我们认为这种相干态可能介导诱导自旋玻璃冻结的“杂质”之间的相互作用。
