Superconductivity at 32K and anisotropy in Tl0.58Rb0.42Fe1.72Se2 crystals

TL;DR

This paper reports the successful growth of Tl0.58Rb0.42Fe1.72Se2 crystals exhibiting superconductivity at 32K, analyzes their anisotropic properties, and discusses the relationship between magnetic fluctuations and superconductivity.

Contribution

It provides new insights into the superconducting properties and anisotropy of Tl0.58Rb0.42Fe1.72Se2 crystals, including critical field measurements and magnetic behavior analysis.

Findings

Superconducting transition at 32K in Tl0.58Rb0.42Fe1.72Se2

Anisotropy ratio of 5.0 for upper critical fields

Presence of strong antiferromagnetic spin fluctuations

Abstract

Single crystals of Tl0.58Rb0.42Fe1.72Se2 are successfully grown with the superconducting transition temperatures Tconset=32K and Tczero=31.4K. The Hall coefficient exhibits a multi-band behavior, which is very similar to that of all other Fe-based superconductors. We found that the susceptibility at the normal state decreases with decreasing the temperature, indicating a strong antiferromagnetic (AFM) spin fluctuation at the normal state, which might be related to the superconductivity (SC). We also determined the upper critical fields in ab-plane and along c-axis. The anisotropy of the superconductivity determined by the ratio of Hc2ab and Hc2c is estimated to 5.0, which is larger than that in (Ba,K)Fe2As2 and BaFe2-xCoxAs2, but smaller than that in cuprate superconductors.