Multiorbital charge-density wave excitations and concomitant phonon anomalies in Bi2Sr2LaCuO6+δ
Multiorbital charge-density wave excitations and concomitant phonon anomalies in Bi2Sr2LaCuO6+δ
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DOI：
10.1073/pnas.2001755117
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发表时间：
2020-07-14
影响因子：
11.1
通讯作者：
Zhou, Ke-Jin
中科院分区：
文献类型：
--
作者：
Li, Jiemin;Nag, Abhishek;Zhou, Ke-Jin
电荷密度波（CDW）在欠掺杂铜氧化物超导体中普遍存在。作为价电子密度的调制，空穴掺杂铜氧化物中的CDW同时具有Cu-3d和O-2 p轨道特征，这是由于这些轨道在费米能级附近的强杂化。本文利用共振非弹性X射线散射（RIXS）研究了欠掺杂Bi_2Sr_1.4La_0.6CuO_6 + δ，发现在氧化铜（CuO_2）面内的Cu和O亚晶格中都存在短程CDW，其周期性和相关长度相当。此外，我们发现键拉伸和键屈曲声子异常伴随着CDW。与稍微过掺杂的Bi_2Sr_1.8La_0.2CuO_6 + δ相比，其中既不出现CDW也不出现声子反常，我们强调在键屈曲声子的CDW波矢（QCDW）附近诱导了尖锐的强度异常，与键伸缩声子在远大于QCDW的波矢处的扩散强度增强相一致。我们的研究结果提供了准静态CDW，它们的色散激发，以及相关的电子-声子异常的全面图片，这是理解铜酸盐中竞争电子不稳定性的关键。
Charge-density waves (CDWs) are ubiquitous in underdoped cuprate superconductors. As a modulation of the valence electron density, CDWs in hole-doped cuprates possess both Cu-3d and O-2p orbital character owing to the strong hybridization of these orbitals near the Fermi level. Here, we investigate underdoped Bi2Sr1.4La0.6CuO6+delta us-ing resonant inelastic X-ray scattering (RIXS) and find that a short-range CDW exists at both Cu and O sublattices in the copper-oxide (CuO2) planes with a comparable periodicity and correlation length. Furthermore, we uncover bond-stretching and bond-buckling phonon anomalies concomitant to the CDWs. Comparing to slightly over -doped Bi2Sr1.8La0.2CuO6+delta, where neither CDWs nor phonon anoma-lies appear, we highlight that a sharp intensity anomaly is induced in the proximity of the CDW wavevector (QCDW) for the bond-buckling phonon, in concert with the diffused intensity enhancement of the bond-stretching phonon at wavevectors much greater than QCDW. Our results provide a comprehensive picture of the quasistatic CDWs, their dispersive excitations, and associated electron-phonon anoma-lies, which are key for understanding the competing electronic insta-bilities in cuprates.