Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O

TL;DR

This study maps the superconducting phase diagram of Na(x)CoO(2).1.3H(2)O, revealing a band-filling dependence of Tc similar to cuprates, which could shed light on high-temperature superconductivity mechanisms.

Contribution

It demonstrates that Na(x)CoO(2).1.3H(2)O exhibits a Tc versus band filling behavior analogous to cuprates, highlighting its potential to inform high-Tc superconductivity theories.

Findings

Superconducting Tc peaks at optimal band filling.

Tc decreases in underdoped and overdoped regimes.

Behavior closely resembles cuprate superconductors.

Abstract

Although the microscopic origin of the superconductivity in high Tc copper oxides remains the subject of active inquiry, several of their electronic characteristics are well established as universal to all the known materials, forming the experimental foundation that all theories must address. The most fundamental of those characteristics is the dependence of the superconducting transition temperature on the degree of electronic band filling. Since the discovery of cuprate superconductivity in 1986 (1), the search for other families of superconductors that might help shed light on the superconducting mechanism of the cuprates has been of great interest. The recent report of superconductivity near 4K in the triangular lattice, layered sodium cobalt oxyhydrate, Na0.35CoO2.1.3H2O, is the best indication that superconductors related to the cuprates may be found (2). Here we show that the superconducting transition temperature of this compound displays the same kind of band-filling behavior that is observed in the cuprates. Specifically, that the optimal superconducting Tc occurs in a narrow range of band filling, and decreases for both underdoped and overdoped materials, in dramatic analogy to the phase diagram of the cuprate superconductors. Our results suggest that characterization of the detailed electronic and magnetic behavior of these new materials may help establish which of the many special characteristics of the cuprates is fundamental to their high Tc superconductivity.