Lightly doping a Mott insulator

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Science  09 Sep 2016:
Vol. 353, Issue 6304, pp. 1110-1111
DOI: 10.1126/science.353.6304.1110-c

Cuprates usually acquire their superconductivity when charged carriers, typically holes, are chemically introduced into a “parent” state called a Mott insulator. However, this part of the cuprate phase diagram is rich in phases, including a pseudogap and a charge-order phase, whose relationship to each other and to superconductivity is under debate. Cai et al. used scanning tunneling spectroscopy of a very lightly doped Bi2Sr2–x LaxCuO6+δ to unravel the phase conundrum. As the hole dopants were introduced, a pseudogap-like density of states started to emerge, followed by a checker-board pattern characteristic of the charge order. When further doping caused the material to become superconductive, the charge-order pattern became less prominent, indicating a competition between the two phases.

Nat. Phys. 10.1038/PHYS3840 (2016).

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