Superconductivity in Na_xCoO_2yH_2O by charge fluctuation

TL;DR

This paper proposes a new mechanism for superconductivity in Na_xCoO_2yH_2O based on charge fluctuations, highlighting the stabilization of f-wave triplet pairing near charge-density-wave instability on a triangular lattice.

Contribution

It introduces a charge fluctuation-based mechanism for superconductivity in a Co-based oxide using a single-band Hubbard model and RPA analysis, emphasizing the role of lattice geometry.

Findings

f-wave triplet superconductivity is stabilized near charge-density-wave instability

Charge fluctuations are key to the superconducting mechanism in this material

Contrast with square-lattice systems in the pairing symmetry and mechanism

Abstract

A new mechanism for superconductivity in the newly discovered Co-based oxide is proposed by using charge fluctuation. A single-band extended Hubbard model on the triangular lattice is studied within random phase approximation. $f$-wave triplet superconductivity is stabilized in the vicinity of charge-density-wave instability, which is in sharp contrast with the square-lattice case. The physical origin of the realization of the $f$-wave triplet state as well as the relevance to experiments are discussed.