LAUSR

The authors analyze a recent STM experiment, reporting a period-8 charge density wave (CDW) in the vortex halo in striking contrast to the period-4 CDWs that are commonly observed in the cuprates. Inside the superconducting dome, the observation of CDWs necessarily implies the existence of a pair density wave (PDW) at the same momentum, as suggested by various theoretical proposals. The authors discuss distinct experimental features, which distiguish the case where this newly reported CDW is driven by a PDW and the case where the CDW is the primary order, and suggest follow-up experiments in order to distinguish unambiguously these two scenarios. The PDW-driven scenario is then put into a broader context in relation to the pseudo-gap phenomenology, H${}_{c}$${}_{2}$, and different kinds of CDWs.