Superconductivity in Ir-doped LaFe1-xIrxAsO

TL;DR

This paper reports the discovery of superconductivity in LaFeAsO induced by doping with the 5d element Ir, achieving superconductivity at 11 K and revealing new insights into the physics of iron-based superconductors.

Contribution

It is the first demonstration of bulk superconductivity in the FeAs-1111 family through substitution of Fe with a higher d-orbital element, Ir.

Findings

Superconductivity observed at 11 K in LaFe1-xIrxAsO.

Upper critical field estimated at about 55 T.

Successful replacement of Fe with Ir confirmed by lattice parameter changes.

Abstract

We report the realization of superconductivity by 5d element Ir doping in LaFeAsO, a prototype parent compound of high-temperature iron based superconductors. X-ray diffraction patterns indicate that the material has formed the ZrCuSiAs-type structure with a space group P4/nmm. The systematic evolution of the lattice constants demonstrated that the Fe ions were successfully replaced by the Ir. Both electrical resistance and magnetization measurements show superconductivity up to 11 K in LaFe1-xIrxAsO. The superconducting transitions at different magnetic fields were also measured yielding a slope of -dHc2/dT = 6.7 T / K near Tc, and the upper critical field at zero K is found to be about 55 T. This is the first example of bulk superconductivity induced by replacing the Fe sites with higher d-orbital electrons in FeAs-1111 family, which should add more ingredients to the underlying physics of the iron-based superconductors.