Phase-fluctuation induced reduction of the kinetic energy at the superconducting transition

الأصل · EN

Recent reflectivity measurements provide evidence for a "violation" of the in-plane optical integral in the underdoped high-Tc compound Bi₂Sr₂CaCu₂O₈₊δ up to frequencies much higher than expected by standard BCS theory. The sum rule violation may be related to a loss of in-plane kinetic energy at the superconducting transition. Here, we show that a model based on phase fluctuations of the superconducting order parameter can account for this change of in-plane kinetic energy at Tc. The change is due to a transition from a phase-incoherent Cooper-pair motion in the pseudogap regime above Tc to a phase-coherent motion at Tc.