Approximate tight-binding sum rule for the superconductivity related change of c-axis kinetic energy in multilayer cuprate superconductors

TL;DR

This paper extends a sum rule to multilayer cuprate superconductors to estimate the change in c-axis kinetic energy below Tc, supporting the interlayer tunnelling mechanism's role in high-Tc superconductivity.

Contribution

It provides a generalized sum rule for multilayer cuprates and estimates the kinetic energy change, linking it to the superconducting condensation energy.

Findings

Hc decreases below Tc in all studied compounds.

The magnitude of Hc change is comparable to the condensation energy.

Results support the interlayer tunnelling mechanism in multilayer HTCS.

Abstract

We present an extension of the c-axis tight-binding sum rule discussed by Chakravarty, Kee, and Abrahams [Phys. Rev. Lett. 82, 2366 (1999)] that applies to multilayer high-Tc cuprate superconductors (HTCS) and use it to estimate--from available infrared data--the change below Tc of the c-axis kinetic energy, Hc, in YBa2Cu3O(7-delta) (delta=0.45,0.25,0.07), Bi2Sr2CaCu2O8, and Bi2Sr2Ca2Cu3O10. In all these compounds Hc decreases below Tc and except for Bi2Sr2CaCu2O8 the change of Hc is of the same order of magnitude as the condensation energy. This observation supports the hypothesis that in multilayer HTCS superconductivity is considerably amplified by the interlayer tunnelling mechanism.