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arXiv 1402.3282cond-mat.str-el
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二维量子反铁磁体Sr2CuO2Cl2的高能磁激发连续谱

High-Energy Continuum of Magnetic Excitations in the Two-Dimensional Quantum Antiferromagnet Sr2CuO2Cl2

K. W. Plumb, A. T. Savici, G. E. Granroth, F. C. Chou, Young-June Kim

摘要:

利用高分辨非弹性中子散射(INS)测量了正方晶格自旋1/2反铁磁体模型$\rm Sr_2CuO_2Cl_2$在宽能量和动量范围内的磁激发谱。沿磁带边界的磁振子色散被精确测量为43 meV,在(1/2,0)和(3/4,1/4)之间,表明自旋哈密顿量中最近邻耦合的重要性。我们观察到一个强的动量依赖阻尼的带边界磁振子在(1/2,0)揭示了一个高能量连续的磁激发。我们的INS测量和共振非弹性X射线散射(RIXS)测量之间的直接比较表明,RIXS光谱包含以前没有考虑过的较高能量激发的显着贡献。我们的观察表明,这种高能量的连续磁场波动是一个无处不在的功能绝缘单层铜氧化物,明显的非弹性中子和光散射测量。

英文摘要:

We have measured the magnetic excitation spectrum of the model square-lattice spin-1/2 antiferromagnet $\rm Sr_2CuO_2Cl_2$ over a broad range of energy and momentum using high-resolution inelastic neutron scattering (INS). The magnon dispersion along the zone boundary was accurately measured to be a 43 meV between (1/2,0) and (3/4,1/4) indicating the importance of coupling beyond nearest neighbors in the spin Hamiltonian. We observe a strong momentum dependent damping of the zone-boundary magnons at (1/2,0) revealing a high energy continuum of magnetic excitations. A direct comparison between our INS measurements and resonant inelastic X-ray scattering (RIXS) measurements shows that the RIXS spectrum contains significant contributions from higher energy excitations not previously considered. Our observations demonstrate that this high-energy continuum of magnetic fluctuations is a ubiquitous feature of insulating monolayer cuprates, apparent in both inelastic neutron and light scattering measurements.

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