Temperature dependence of the spectral weight in p- and n-type cuprates: a study of normal state partial gaps and electronic kinetic energy

TL;DR

This study investigates how the spectral weight and partial gaps in the normal state of p- and n-type cuprates vary with temperature, revealing differences in electronic behavior and kinetic energy changes across the superconducting transition.

Contribution

It provides detailed optical conductivity measurements and analyzes the temperature dependence of spectral weight, highlighting differences between p- and n-type cuprates and their relation to Mott physics.

Findings

Partial gap opening in n-type PCCO but not in p-type BSCCO.

Spectral weight change at Tc shows a crossover from BCS to unconventional behavior in BSCCO.

Electronic kinetic energy behavior is linked to spectral weight loss and superfluid formation.

Abstract

The optical conductivity of CuO2 (copper-oxygen) planes in p- and n-type cuprates thin films at various doping levels is deduced from highly accurate reflectivity data. The temperature dependence of the real part sigma1(omega) of this optical conductivity and the corresponding spectral weight allow to track the opening of a partial gap in the normal state of n-type Pr{2-x}Ce(x)CuO4 (PCCO), but not of p-type Bi2Sr2CaCu2O(8+delta} (BSCCO) cuprates. This is a clear difference between these two families of cuprates, which we briefly discuss. In BSCCO, the change of the electronic kinetic energy Ekin - deduced from the spectral weight- at the superconducting transition is found to cross over from a conventional BCS behavior (increase of Ekin below Tc to an unconventional behavior (decrease of Ekin below Tc) as the free carrier density decreases. This behavior appears to be linked to the energy scale over which spectral weight is lost and goes into the superfluid condensate, hence may be related to Mott physics.