Peng Y Y, Fumagalli R, Ding Y, Minola M, Caprara S, Betto D, Bluschke M, De Luca G M, Kummer K, Lefrançois E, Salluzzo M, Suzuki H, Le Tacon M, Zhou X J, Brookes N B, Keimer B, Braicovich L, Grilli M, Ghiringhelli G
Dipartimento di Fisica, Politecnico di Milano, Milano, Italy.
Department of Physics and Seitz Materials Research Laboratory, University of Illinois, Urbana, IL, USA.
Nat Mater. 2018 Aug;17(8):697-702. doi: 10.1038/s41563-018-0108-3. Epub 2018 Jun 11.
In the underdoped regime, the cuprate high-temperature superconductors exhibit a host of unusual collective phenomena, including unconventional spin and charge density modulations, Fermi surface reconstructions, and a pseudogap in various physical observables. Conversely, overdoped cuprates are generally regarded as conventional Fermi liquids possessing no collective electronic order. In partial contradiction to this widely held picture, we report resonant X-ray scattering measurements revealing incommensurate charge order reflections for overdoped (Bi,Pb)SrCuO (Bi2201), with correlation lengths of 40-60 lattice units, that persist up to temperatures of at least 250 K. The value of the charge order wavevector decreases with doping, in line with the extrapolation of the trend previously observed in underdoped Bi2201. In overdoped materials, however, charge order coexists with a single, unreconstructed Fermi surface without nesting or pseudogap features. The discovery of re-entrant charge order in Bi2201 thus calls for investigations in other cuprate families and for a reconsideration of theories that posit an essential relationship between these phenomena.
在欠掺杂区域，铜酸盐高温超导体表现出许多不寻常的集体现象，包括非常规的自旋和电荷密度调制、费米面重构以及各种物理可观测量中的赝能隙。相反，过掺杂的铜酸盐通常被视为不具有集体电子序的常规费米液体。与这种广泛持有的观点部分矛盾的是，我们报告了共振X射线散射测量结果，揭示了过掺杂的(Bi,Pb)SrCuO（Bi2201）中存在非 commensurate电荷序反射，其关联长度为40 - 60个晶格单位，这种电荷序一直持续到至少250 K的温度。电荷序波矢的值随掺杂而减小，这与之前在欠掺杂Bi2201中观察到的趋势外推结果一致。然而，在过掺杂材料中，电荷序与单一的、未重构的费米面共存，且不存在嵌套或赝能隙特征。因此，在Bi2201中发现的再入式电荷序要求对其他铜酸盐家族进行研究，并重新考虑那些假定这些现象之间存在本质关系的理论。
