Local Ordering in the Pseudogap State of the High-T$_c$ Superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$

TL;DR

This study uses atomic-scale techniques to reveal energy-independent, incommensurate spatial modulations in the pseudogap state of Bi$_2$Sr$_2$CaCu$_2$O$_{8+eta}$, suggesting an electronic ordering phenomenon linked to the pseudogap.

Contribution

It provides direct atomic-scale evidence of spatial modulations in the pseudogap state, offering new insights into electronic ordering in high-Tc cuprates.

Findings

Energy-independent incommensurate modulations along Cu-O bonds

Modulations correlate with the pseudogap in electronic density

Results challenge existing theories of the pseudogap origin

Abstract

We report atomic scale characterization of the pseudogap state in a high-T$_c$ superconductor, Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. The electronic states at low energies within the pseudogap exhibit spatial modulations having an energy-independent incommensurate periodicity. These patterns, which are oriented along the copper-oxygen bond directions, appear to be a consequence of an electronic ordering phenomenon--the observation of which correlates with the pseudogap in the density of electronic states. Our results provide a stringent test for various ordering scenarios in the cuprates, which have been central in the debate on the nature of the pseudogap and the complex electronic phase diagram of these compounds.