Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
Phys Rev Lett. 2012 Sep 14;109(11):117207. doi: 10.1103/PhysRevLett.109.117207.
Ca(2)Y(2)Cu(5)O(10) is built up from edge-shared CuO(4) plaquettes forming spin chains. From inelastic neutron scattering data we extract an in-chain nearest-neighbor exchange J(1)≈-170 K and the frustrating next-neighbor J(2)≈32 K interactions, both significantly larger than previous estimates. The ratio α=|J(2)/J(1)|=0.19±0.01 places the system close to the critical point α(c)=0.25 of the J(1)-J(2) chain but in the 1D ferromagnetic regime. We establish that the vicinity to criticality only marginally affects the dispersion and coherence of the spin-wave-like magnetic excitations but instead results in a dramatic T dependence of high-energy Zhang-Rice singlet excitation intensities.
Ca(2)Y(2)Cu(5)O(10) 由边缘共享的 CuO(4) 薄片构成自旋链。从非弹性中子散射数据中，我们提取出链内最近邻交换 J(1)≈-170 K 和令人沮丧的次近邻 J(2)≈32 K 相互作用，两者都明显大于以前的估计。比率 α=|J(2)/J(1)|=0.19±0.01 表明该系统接近 J(1)-J(2)链的临界点 α(c)=0.25，但处于一维铁磁态。我们确定，接近临界点仅略微影响自旋波状磁激发的色散和相干性，但会导致高能 Zhang-Rice 单重态激发强度随温度的急剧变化。
