Water Content and Superconductivity in Na0.3CoO2*yH2O

TL;DR

This study explores how water content affects superconductivity in Na0.3CoO2*yH2O, revealing that water influences superconducting properties and intergrowth structures, with implications for understanding the material's quasi-2D superconductivity.

Contribution

It provides new insights into the relationship between water content, intergrowths, and superconductivity in Na0.3CoO2*yH2O, highlighting the effects of temperature and cold compression.

Findings

Water content correlates with superconductivity and intergrowth structures.

Superconducting transition temperature shifts minimally with water content.

Water loss reduces diamagnetization, indicating weak links.

Abstract

We report here the correlation between the water content and superconductivity in Na0.3CoO2*yH2O under the influences of elevated temperature and cold compression. The x-ray diffraction of the sample annealed at elevated temperatures indicates that intergrowths exist in the compound at equilibrium when 0.6 < y < 1.4. Its low-temperature diamagnetization varies linearly with y, but is insensitive to the intergrowth, indicative of quasi-2D superconductivity. The Tc-onset, especially, shifts only slightly with y. Our data from cold compressed samples, on the other hand, show that the water-loss non-proportionally suppresses the diamagnetization, which is suggestive of weak links.