Ying T, Schmidt K P, Wessel S
Institut für Theoretische Festkörperphysik, JARA-FIT and JARA-HPC, RWTH Aachen University, 52056 Aachen, Germany.
Department of Physics, Harbin Institute of Technology, 150001 Harbin, China.
Phys Rev Lett. 2019 Mar 29;122(12):127201. doi: 10.1103/PhysRevLett.122.127201.
Polarized inelastic neutron scattering experiments recently identified the amplitude (Higgs) mode in C_{9}H_{18}N_{2}CuBr_{4}, a two-dimensional near-quantum-critical spin-1/2 two-leg ladder compound, which exhibits a weak easy-axis exchange anisotropy. Here, we theoretically examine the dynamic spin structure factor of such planar coupled spin-ladder systems using large-scale quantum Monte Carlo simulations. This allows us to provide a quantitative account of the experimental neutron scattering data within a consistent quantum spin model. Moreover, we trace the details of the continuous evolution of the amplitude mode from a two-particle bound state of coupled ladders in the classical Ising limit all the way to the quantum spin-1/2 Heisenberg limit with fully restored SU(2) symmetry, where it gets overdamped by the two-magnon continuum in neutron scattering.
极化非弹性中子散射实验最近在二维近量子临界自旋 - 1/2 两腿梯子化合物 C₉H₁₈N₂CuBr₄ 中识别出振幅（希格斯）模式，该化合物表现出弱的易轴交换各向异性。在此，我们使用大规模量子蒙特卡罗模拟从理论上研究此类平面耦合自旋梯子系统的动态自旋结构因子。这使我们能够在一致的量子自旋模型内对实验中子散射数据进行定量描述。此外，我们追踪了振幅模式从经典伊辛极限下耦合梯子的两粒子束缚态一直到具有完全恢复的 SU(2) 对称性的量子自旋 - 1/2 海森堡极限的连续演化细节，在该极限下它在中子散射中被双磁振子连续谱过度阻尼。
