hide
Free keywords:
-
Abstract:
An unidentified quantum fluid designated the pseudogap (PG) phase is produced by electron-density depletion in the CuO2 antiferromagnetic insulator. Current theories suggest that the PG phase may be a pair density wave (PDW) state characterized by a spatially modulating density of electron pairs. Such a state should exhibit a periodically modulating energy gap Delta(P)(r) in real-space, and a characteristic quasiparticle scattering interference (QPI) signature Lambda(P)(q) in wavevector space. By studying strongly underdoped Bi2Sr2CaDyCu2O8 at hole-density similar to-0.08 in the superconductive phase, we detect the 8a(0)-periodic Delta(P)(r)modulations signifying a PDW coexisting with superconductivity. Then, by visualizing the temperature dependence of this electronic structure from the superconducting into the pseudogap phase, we find the evolution of the scattering interference signature Lambda(q) that is predicted specifically for the temperature dependence of an 8a(0)-periodic PDW. These observations are consistent with theory for the transition from a PDW state coexisting with d-wave superconductivity to a pure PDW state in the Bi2Sr2CaDyCu2O8 pseudogap phase. The pseudogap phase in cuprate superconductors is predicted to be a pair density wave state (PDW) but experimental evidence has been lacking. Here, the authors detect the temperature evolution of energy gap modulations and scattering interference signature suggesting the Bi2Sr2CaDyCu2O8 pseudogap phase contains a PDW.
