Direct evidence of pairing up to pseudogap energy in cuprate high-temperature superconductors: Part II

In the cuprate high-temperature superconductors, the pseudogap phase connects the Mott insulator and superconductivity phases. Despite extensive research, the origin of the pseudogap remains elusive. A key question, debated for decades, is whether the pseudogap is associated with electron pairing, or if it corresponds to a local ordered state. Shot noise experiments, which can directly detect electron pairing, have the potential to resolve this long-standing debate.

In this talk, I will present the results of local shot-noise measurements on the unconventional superconductor Bi2Sr2CaCu2O8+p [1]. Our data demonstrates that the pseudogap energy is associated with electron pairing, with pairing energies reaching up to 70 meV. This finding excludes the possibility of the pseudogap arising solely from local orders, and instead indicates a clear relation between the pseudogap phase and Cooper pair formation. Furthermore, we observe that the pairing energy is spatially heterogeneous.

[1] J. Niu* & M. Ortego Larrazabal* et. al., Equivalence of pseudogap and pairing energy in a cuprate high-temperature superconductor, arXiv:2409.15928.