Commensurate 4<i>a</i><sub>0</sub>-period charge density modulations throughout the Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8+x</sub> pseudogap regime.

Mesaros, Andrej; Fujita, Kazuhiro; Edkins, Stephen D; Hamidian, Mohammad H; Eisaki, Hiroshi; Uchida, Shin-Ichi; Davis, J C Séamus; Lawler, Michael J et al. · Proc Natl Acad Sci U S A · 2016

basic_science · Level V

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Abstract

Theories based upon strong real space (<i>r</i>-space) electron-electron interactions have long predicted that unidirectional charge density modulations (CDMs) with four-unit-cell (4<i>a</i><sub>0</sub>) periodicity should occur in the hole-doped cuprate Mott insulator (MI). Experimentally, however, increasing the hole density <i>p</i> is reported to cause the conventionally defined wavevector <i>Q</i><sub><i>A</i></sub> of the CDM to evolve continuously as if driven primarily by momentum-space (<i>k</i>-space) effects. Here we introduce phase-resolved electronic structure visualization for determination of the cuprate CDM wavevector. Remarkably, this technique reveals a virtually doping-independent locking of the local CDM wavevector at [Formula: see text] throughout the underdoped phase diagram of the canonical cuprate Bi<sub>2</sub>Sr<sub>2</sub>CaCu<sub>2</sub>O<sub>8</sub> These observations have significant fundamental consequences because they are orthogonal to a <i>k</i>-space (Fermi-surface)-based picture of the cuprate CDMs but are consistent with strong-coupling <i>r</i>-space-based theories. Our findings imply that it is the latter that provides the intrinsic organizational principle for the cuprate CDM state.