School of Physics & Astronomy, University of St-Andrews, the North Haugh, St Andrews, KY16 9SS, United Kingdom.
Phys Rev Lett. 2009 Dec 4;103(23):237201. doi: 10.1103/PhysRevLett.103.237201. Epub 2009 Dec 2.
Neutron spectroscopy and diffuse neutron scattering on herbertsmithite [ZnCu(3)(OH)(6)Cl(2)], a near-ideal realization of the s=1/2 kagome antiferromagnet, reveal the hallmark property of a quantum spin liquid: instantaneous short-ranged antiferromagnetic correlations in the absence of a time-averaged ordered moment. These dynamic antiferromagnetic correlations are weakly dependent of neutron-energy transfer and temperature, and persist up to 25 meV and 120 K. At low energy transfers a shift of the magnetic scattering to low Q is observed with increasing temperature, providing evidence of gapless spinons. It is argued that these observations provide important evidence in favor of resonating-valence-bond theories of (doped) Mott insulators.
在方钴矿 [ZnCu(3)(OH)(6)Cl(2)] 上进行的中子能谱学和漫散射实验研究，这是对近理想的 s=1/2 kagome 反铁磁体的实现，揭示了量子自旋液体的标志性特性：在没有时间平均有序矩的情况下，瞬时的短程反铁磁关联。这些动态反铁磁关联对中子能量转移和温度的依赖性较弱，并且在 25 meV 和 120 K 时仍然存在。在低能量转移下，随着温度的升高，磁散射向低 Q 移动，这为无能隙自旋子提供了证据。有人认为，这些观察结果为（掺杂）Mott 绝缘体的共振价带理论提供了重要证据。
