Superconductivity in Na$_{x}$CoO$_{2}\cdot y$H$_{2}$O driven by the kinetic energy

TL;DR

This paper explores how superconductivity in Na$_{x}$CoO$_{2}\\cdot y$H$_{2}$O arises from kinetic energy-driven interactions between dressed fermions, aligning with experimental doping-dependent transition temperatures.

Contribution

It introduces a kinetic energy-based mechanism for superconductivity in Na$_{x}$CoO$_{2}\\cdot y$H$_{2}$O using the charge-spin separation fermion-spin theory, highlighting magnetic excitation exchange.

Findings

Superconductivity is driven by kinetic energy interactions via magnetic excitations.

Optimal transition temperature occurs at doping level ~0.29.

Transition temperature decreases in both underdoped and overdoped regimes.

Abstract

Within the charge-spin separation fermion-spin theory, the mechanism of superconductivity in Na$_{x}$CoO$_{2}\cdot y$H$_{2}$O is studied. It is shown that dressed fermions interact occurring directly through the kinetic energy by exchanging magnetic excitations. This interaction leads to a net attractive force between dressed fermions(then the electron Cooper pairs), and their condensation reveals the superconducting ground state. The optimal superconducting transition temperature occurs in the electron doping concentration $\delta\approx 0.29$, and then decreases for both underdoped and overdoped regimes, in qualitative agreement with the experimental results.