Synthesis of ErFeAsO-based superconductors by hydrogen doping method

TL;DR

This paper presents a hydrogen doping technique to synthesize ErFeAsO-based superconductors with minimal lattice constants, achieving high critical temperatures around 44 K, and discusses the phase diagram of Tc dependence on lanthanide elements.

Contribution

The study introduces a novel hydrogen doping method for stabilizing ErFeAsO-based superconductors with small lattice constants and high Tc, expanding the understanding of phase diagrams in LnFeAsO systems.

Findings

Achieved Tc of 44.5 K in ErFeAsO-based superconductor.

Successfully stabilized ErFeAsO with the smallest lattice constants in the series.

Provided insights into the Ln dependence of Tc in LnFeAsO superconductors.

Abstract

Here we demonstrate the technique to stabilize the ErFeAsO-based superconductor with the smallest lattice constants in LnFeAsO1-y (Ln = lanthanide) series using hydrogen doping method. Polycrystalline samples were synthesized by heating pellets with nominal compositions of ErFeAsO1-y (1-y = 0.75 ~ 0.95) sandwiched between pellets of LaFeAsO0.8H0.8 compositions at 1100 {\deg}C under a pressure of 5.0 - 5.5 GP. The sample with lattice constants of a = 3.8219 {\AA} and c = 8.2807 {\AA} shows the highest superconducting critical temperatures (Tc) of 44.5 K and 41.0 K determined by onset transitions of resistivity and susceptibility, respectively. We discuss phase diagram of Ln dependence of Tc in LnFeAsO-based superconductors.