Incipient charge order observed by NMR in the normal state of YBa ₂Cu ₃O _y

Abstract

The pseudogap regime of high-temperature cuprates harbours diverse manifestations of electronic ordering whose exact nature and universality remain debated. Here, we show that the short-ranged charge order recently reported in the normal state of YBa ₂Cu ₃O _y corresponds to a truly static modulation of the charge density. We also show that this modulation impacts on most electronic properties, that it appears jointly with intra-unit-cell nematic, but not magnetic, order, and that it exhibits differences with the charge density wave observed at lower temperatures in high magnetic fields. These observations prove mostly universal, they place new constraints on the origin of the charge density wave and they reveal that the charge modulation is pinned by native defects. Similarities with results in layered metals such as NbSe ₂, in which defects nucleate halos of incipient charge density wave at temperatures above the ordering transition, raise the possibility that order–parameter fluctuations, but no static order, would be observed in the normal state of most cuprates if disorder were absent.

Abstract

The nature and universality of the ordering phenomena observed in the normal state of high-temperature superconductors remain unclear. Here, Wu et al. observe several aspects of incipient charge ordering in YBCO via NMR measurements, clarifying the role of quenched disorder in their emergence.