Superconductivity and Phase Diagram in the Iron-based Arsenic-oxides ReFeAsO1-delta (Re = rare earth metal) without F-Doping

TL;DR

This paper reports the synthesis of new iron-based superconductors without fluorine doping, showing high critical temperatures up to 55 K and a dome-shaped phase diagram related to oxygen content.

Contribution

It introduces a new class of superconductors synthesized under high pressure without F-doping, expanding understanding of phase diagrams in ReFeAsO1-delta compounds.

Findings

Superconductivity achieved without fluorine doping.

Maximum Tc of 55 K in SmFeAsO1-delta.

Dome-shaped phase diagram with oxygen variation.

Abstract

Here we report a new class of superconductors prepared by high pressure synthesis in the quaternary family ReFeAsO1-delta (Re = Sm, Nd, Pr, Ce, La) without fluorine doping. The onset superconducting critical temperature (Tc) in these compounds increases with the reduction of Re atom size, and the highest Tc obtained so far is 55 K in SmFeAsO1-delta. For the NdFeAsO1-delta system with different oxygen concentration a dome-shaped phase diagram was found.