Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
J Phys Condens Matter. 2013 Sep 4;25(35):356002. doi: 10.1088/0953-8984/25/35/356002. Epub 2013 Aug 5.
LuCuGaO₄ has magnetic Cu(2+) and diamagnetic Ga(3+) ions distributed on a triangular bilayer and is suggested to undergo a spin glass transition at Tg ∼ 0.4 K. Using μSR (muon spin rotation) and neutron scattering measurements, we show that at low temperature the spins form a short range correlated state with spin fluctuations detectable over a wide range of timescales: at 0.05 K magnetic fluctuations can be detected in both the μSR time window and also extending beyond 7 meV in the inelastic neutron scattering response, indicating magnetic fluctuations spanning timescales between ∼10(-5) and ∼10(-10) s. The dynamical susceptibility scales according to the form χ″(ω)T(α), with α = 1, throughout the measured temperature range (0.05-50 K). These effects are associated with quantum fluctuations and some degree of structural disorder in ostensibly quite different materials, including certain heavy fermion alloys, kagome spin liquids, quantum spin glasses, and valence bond glasses. We therefore suggest that LuCuGaO₄ is an interesting model compound for the further examination of disorder and quantum magnetism.
LuCuGaO₄ 中具有磁矩的 Cu(2+)和抗磁性的 Ga(3+)离子分布在三角形双层结构中，据推测其在 Tg ∼ 0.4 K 时会发生自旋玻璃转变。我们使用 μSR（μ子自旋旋转）和中子散射测量表明，在低温下，自旋形成了一个短程关联态，自旋涨落在很宽的时间范围内都可被探测到：在 0.05 K 时，在 μSR 时间窗口中可以检测到磁涨落，在弹性中子散射响应中也可以延伸到 7 meV 以上，这表明磁涨落在约 10(-5)到约 10(-10) s 的时间范围内变化。动力学磁化率按照 χ″(ω)T(α)的形式在整个测量温度范围内（0.05-50 K）进行标度，其中 α = 1。这些效应与量子涨落和一定程度的结构无序有关，涉及到各种不同的材料，包括某些重费米合金、 kagome 自旋液体、量子自旋玻璃和价带玻璃。因此，我们认为 LuCuGaO₄ 是进一步研究无序和量子磁性的有趣模型化合物。
