High-energy magnetic excitations in overdoped La 2 - x Sr x CuO 4 studied by neutron and resonant inelastic x-ray scattering
High-energy magnetic excitations in overdoped La 2 - x Sr x CuO 4 studied by neutron and resonant inelastic x-ray scattering
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DOI：
10.1103/physrevb.91.184513
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发表时间：
2015-05
影响因子：
3.7
通讯作者：
S. Wakimoto;K. Ishii;H. Kimura;M. Fujita;G. Dellea;K. Kummer;L. Braicovich;G. Ghiringhelli;L. Debeer-Schmitt;G. Granroth
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文献类型：
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作者：
S. Wakimoto;K. Ishii;H. Kimura;M. Fujita;G. Dellea;K. Kummer;L. Braicovich;G. Ghiringhelli;L. Debeer-Schmitt;G. Granroth
我们已经进行了中子非弹性散射和共振非弹性X射线散射（RIXS）在Cu-L3边缘研究高能量的磁激发在能量转移超过100 meV的过掺杂的La 2 xSrxCuO 4与x=0.25（Tc=15 K）和x=0.30（非超导）使用相同的单晶样品的两种技术。从中子散射截面的恒定能量切片，我们已经确定了磁激发高达~250毫电子伏x=0.25。虽然在动量方向上的宽度很大，但在（π，π）方向上的沿着峰位符合未掺杂La_2CuO_4（LCO）中自旋波的色散关系，这与前人对铜氧化物超导体的RIXS结果一致。利用Cu-L3边的RIXS，我们测量了顺磁模沿着（π，π）和（π，0）两个方向的色散关系。虽然在两个方向上中子和RIXS的数据相互联系，并且顺磁子沿着（π，0）方向与LCO的自旋波色散很好地吻合，但RIXS探测的顺磁子在（π，π）方向上的色散较小，激发能在（π/2，π/2）附近低于LCO的自旋波。因此，我们的结果表明中子非弹性散射和RIXS之间的一致性，并阐明了整个磁激发更多»（π，π）方向的互补使用两个探针。RIXS剖面的极化依赖性表明，在磁激发的相同能量范围内存在明显的电荷激发，反映了过掺杂样品的巡回特征。最后，我们发现电荷激发强度的可能各向异性可以解释由X射线散射检测到的顺磁振子色散在（π，π）方向上的明显差异。«少
We have performed neutron inelastic scattering and resonant inelastic x-ray scattering (RIXS) at the Cu-L3 edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La2₋xSrxCuO4 with x=0.25 (Tc=15 K) and x=0.30 (nonsuperconducting) using identical single-crystal samples for the two techniques. From constant-energy slices of neutron-scattering cross sections, we have identified magnetic excitations up to ~250 meV for x=0.25. Although the width in the momentum direction is large, the peak positions along the (π,π) direction agree with the dispersion relation of the spin wave in the nondoped La2CuO4 (LCO), which is consistent with the previous RIXS results of cuprate superconductors. Using RIXS at the Cu-L3 edge, we have measured the dispersion relations of the so-called paramagnon mode along both (π,π) and (π,0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (π,0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (π,π) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin wave of LCO near (π/2,π/2). Thus, our results indicate consistency between neutron inelastic scattering and RIXS, and elucidate the entire magnetic excitation inmore » the (π,π) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. Lastly, we find a possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (π,π) direction as detected by the x-ray scattering.« less