Superconductivity in layered iron Selenide induced by cobalt- and sodium-doping

TL;DR

This study demonstrates that doping cobalt and sodium into alfa-FeSe induces superconductivity with transition temperatures up to 8.4 K, highlighting new doping mechanisms and the first sodium intercalation-induced superconductivity in this material.

Contribution

It introduces sodium intercalation as a novel doping method to induce superconductivity in alfa-FeSe, alongside cobalt substitution.

Findings

Superconductivity achieved at Tc up to 8.4 K and 8.3 K.

Cobalt doping substitutes Fe sites; sodium doping intercalates between layers.

First demonstration of sodium intercalation inducing superconductivity in alfa-FeSe.

Abstract

Superconductivity with zero resistance transition temperature (Tc) up to 8.4 K and 8.3 K can be obtained by doping cobalt and sodium in alfa-FeSe with the nominal composition of Fe0.92Co0.08Se and Na0.1FeSe, respectively. The electrical resistivity and AC magnetic susceptibility of the prepared samples, measured with physical property measurement system (PPMS), unambiguously consistent with each other to indicate that the samples are superconductive. The respective doping mechanisms for cobalt and sodium into the parent alfa-FeSe are the Fe-site substitution and the interlayer insertion. It is the first time that alfa-FeSe can be induced to be a superconductor with Na+ intercalated into the interlayers.