Superconducting to spin glass state transformation in {\ss}-pyrochlore KxOs2O6

TL;DR

This study investigates the transformation of superconducting KOs2O6 into a spin glass-like state through electrochemical potassium de-intercalation, revealing the role of defects and phase coherence in the material's electronic properties.

Contribution

It provides new insights into how electrochemical potassium removal induces a transition from superconductivity to spin glass behavior in KOs2O6, highlighting the importance of defects and phase coherence.

Findings

Superconductivity in KOs2O6 is suppressed by potassium reduction.

Spin glass-like behavior emerges below ~6.1K after potassium de-intercalation.

Electrochemical de-intercalation reveals two-phase regions and the importance of defects.

Abstract

{\ss}-pyrochore KOs2O6, which shows superconductivity below ~ 9.7K, has been converted into KxOs2O6 (x < 2/3 - 1/2) electrochemically to show spin glass-like behavior below ~ 6.1K. Room temperature sample surface potential versus charge transfer scan indicates that there are at least two two-phase regions for x between 1 and 0.5. Rattling model of superconductivity for the title compound has been examined using electrochemical potassium de-intercalation. The significant reduction of superconducting volume fraction due to minor potassium reduction suggests the importance of defect and phase coherence in the rattling model. Magnetic susceptibility, resistivity, and specific heat measurement results have been compared between the superconducting and spin glass-like samples.