Abstract
Although charge density waves (CDWs) are omnipresent in cuprate high-temperature superconductors, they occur at significantly different wave vectors, confounding efforts to understand their formation mechanism. Here, we use resonant inelastic x-ray scattering to investigate the doping- and temperature-dependent CDW evolution in (). We discover that the CDW develops in two stages with decreasing temperature. A precursor CDW with a quasicommensurate wave vector emerges first at high temperature. This doping-independent precursor CDW correlation originates from the CDW phase mode coupled with a phonon and “seeds” the low-temperature CDW with a strongly doping-dependent wave vector. Our observation reveals the precursor CDW and its phase mode as the building blocks of the highly intertwined electronic ground state in the cuprates.
- Received 22 April 2019
- Revised 5 July 2019
DOI:https://doi.org/10.1103/PhysRevX.9.031042
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Many copper-based high-temperature superconductors (known as cuprates) have periodic patterns in their conduction electrons known as charge-density waves (CDWs). Understanding this connection could provide insight into superconductivity, but researchers do not yet understand how CDWs arise or their connection with other exotic electronic behaviors. Here, we reveal for the first time how CDWs emerge and evolve as a function of both temperature and impurity concentration in a type of cuprate superconductor.
We discover that the CDW develops in two stages with decreasing temperature. A precursor CDW, with the wave vector quasicommensurate with the atomic lattice, emerges first at high temperature. This doping-independent precursor modulation of electrons originates from a coupled CDW-lattice excitation and “seeds” the low-temperature CDW, which has a strongly doping-dependent wave vector.
Our observation reveals the precursor CDW and its phase mode as the common thread of underdoped cuprates, which has important implications for the highly intertwined electronic ground state. Our results thus provide a vital new characterization of the electronic state from which high-temperature superconductivity emerges.