Minola M, Lu Y, Peng Y Y, Dellea G, Gretarsson H, Haverkort M W, Ding Y, Sun X, Zhou X J, Peets D C, Chauviere L, Dosanjh P, Bonn D A, Liang R, Damascelli A, Dantz M, Lu X, Schmitt T, Braicovich L, Ghiringhelli G, Keimer B, Le Tacon M
Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
CNISM, CNR-SPIN and Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy.
Phys Rev Lett. 2017 Sep 1;119(9):097001. doi: 10.1103/PhysRevLett.119.097001. Epub 2017 Aug 31.
Spin excitations in the overdoped high temperature superconductors Tl_{2}Ba_{2}CuO_{6+δ} and (Bi,Pb){2}(Sr,La){2}CuO_{6+δ} were investigated by resonant inelastic x-ray scattering (RIXS) as functions of doping and detuning of the incoming photon energy above the Cu-L_{3} absorption peak. The RIXS spectra at optimal doping are dominated by a paramagnon feature with peak energy independent of photon energy, similar to prior results on underdoped cuprates. Beyond optimal doping, the RIXS data indicate a sharp crossover to a regime with a strong contribution from incoherent particle-hole excitations whose maximum shows a fluorescencelike shift upon detuning. The spectra of both compound families are closely similar, and their salient features are reproduced by exact-diagonalization calculations of the single-band Hubbard model on a finite cluster. The results are discussed in the light of recent transport experiments indicating a quantum phase transition near optimal doping.
通过共振非弹性X射线散射（RIXS）研究了过掺杂高温超导体Tl₂Ba₂CuO₆₊δ和（Bi，Pb）₂（Sr，La）₂CuO₆₊δ中的自旋激发，作为掺杂以及入射光子能量在Cu-L₃吸收峰之上失谐的函数。最佳掺杂时的RIXS光谱主要由一个顺磁子特征主导，其峰值能量与光子能量无关，这与先前对欠掺杂铜酸盐的研究结果类似。超过最佳掺杂后，RIXS数据表明向一个由非相干粒子-空穴激发起主要作用的区域急剧转变，其最大值在失谐时呈现出类似荧光的位移。这两个化合物家族的光谱非常相似，并且它们的显著特征通过有限团簇上单带哈伯德模型的精确对角化计算得以重现。根据最近表明在最佳掺杂附近存在量子相变的输运实验对结果进行了讨论。
