Charge-stripe crystal phase in an insulating cuprate

Abstract

High-Tc superconductivity in cuprates is generally believed to arise from carrier doping an antiferromagnetic Mott (AFM) insulator. Theoretical proposals and emerging experimental evidence suggest that this process leads to the formation of intriguing electronic liquid crystal phases 1 . These phases are characterized by ordered charge and/or spin density modulations, and thought to be intimately tied to the subsequent emergence of superconductivity. The most elusive, insulating charge-stripe crystal phase is predicted to occur when a small density of holes is doped into the charge-transfer insulator state 1-3 , and would provide a missing link between the undoped parent AFM phase and the mysterious, metallic "pseudogap". However, due to experimental challenges, it has been difficult to observe this phase. Here, we use surface annealing to extend the accessible doping range in Bi-based cuprates and achieve the lightly-doped charge-transfer insulating state of a cuprate Bi2Sr2CaCu2O8+x. In this insulating state with a charge transfer gap at the order of ~1 eV, using spectroscopic-imaging scanning tunneling microscopy, we discover a unidirectional charge-stripe order with a commensurate 4a0 period along the Cu-O-Cu bond. Importantly, this insulating charge-stripe crystal phase develops before the onset of the pseudogap and the formation of the Fermi surface. Our work provides new insights into the microscopic origin of electronic inhomogeneity in high-Tc cuprates.

Density Wave Probes Cuprate Quantum Phase Transition

“…1a). Furthermore, while our data do not rule out a small doping dependence, recent experiments on Bi2212 [46][47][48] and very underdoped Bi2201 [30] are also consistent with a Q = 0.25 r.l.u. commensurate DW within the Fermi arc regime arising from proximity to the Mott insulating state.…”

Atomic-scale fragmentation and collapse of antiferromagnetic order in a doped Mott insulator

“…In contrast to cuprates where the AF Mott state is suppressed by ~0.05 holes per Cu site, the AF Mott state in Sr-214 is only partially quenched even at the highest achievable doping of ~ 0.12 electrons per Ir site (14,32). Moreover, compared to a relatively large charge gap in insulating cuprates (11,33), a smaller gap in lightly-doped, insulating Sr-214 allows tunneling experiments to be more easily performed (4,34). As such, this system presents an ideal platform to investigate the interplay of magnetism and electronic correlations within the lightlydoped Mott state.…”

Coulomb blockade effects in a topological insulator grown on a high-Tc cuprate superconductor

“…Second crucial issue is that the electronic properties of the Bi-2212 surface can change upon heating 23 . At ideal Bi 2 Te 3 growth temperatures of~350°C 24 , interstitial oxygen dopants escape from the topmost surface layers of Bi-2212, leading to an effective lowering of the hole density and degradation of superconducting properties 23 . To mitigate this issue, in this work we use much lower Bi 2 Te 3 growth temperatures below 250°C (Supplementary Note 1).…”