Here's a quote from a recent article titled: Asymmetric Feature Shows Puzzling Face For Superconductivity

"Below the superconducting transition, the tunneling conductance showed a large unexpected asymmetrical feature near zero bias," Eckstein said.

"This is evidence that crystals of high-temperature superconductors, atomically truncated with a titanate layer, have intrinsically broken particle-hole symmetry."

(...)

"This clearly demonstrates the breaking of symmetry between particle-like and hole-like excitations at this interface in the superconducting state," Eckstein said.

Yes, clearly, that's the case.