High-temperature superconductivity in monolayer Bi2Sr2CaCu2O8+δ

Fig. 6 | Electronic structure of monolayer Bi-2212 in the Mott insulating 
regime. a, Spatially averaged differential conductance spectra of monolayer
Bi-2212 obtained between vacuum annealing cycles. The annealing temperature 
is marked on each curve. The spectrum labelled ‘Initial’ was recorded before 
annealing. The as-exfoliated monolayer (obtained from OD55 crystal) was 
initially over-doped. The annealing cycles progressively lower its doping level 
and eventually make the specimen extremely under-doped. b, Representative 
tunnelling spectra of the extremely under-doped monolayer in a. Inset: 
tunnelling conductance maps recorded at tunnelling biases of 0.2 V (upper 
panel) and 1.6 V (lower panel). Crosses mark the positions where the spectra are 
taken. Spectra are shifted vertically for clarity.

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8 | Nature | www.nature.com
Article
indicate that the dimensionality effect, if it exists at all, does not
play an important role in the transition from Mott to pseudogap phase 
in Bi-2212.
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are available at https://doi.org/10.1038/s41586-019-1718-x.
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