Possible hydrogen doping and enhancement of Tc (= 35 K) in a LaFeAsO-based superconductor

TL;DR

This study demonstrates that hydroxide ion incorporation in LaFeAsO-based superconductors significantly raises the superconducting transition temperature (Tc) to 35 K, surpassing previous doping methods, with confirmed hydrogen presence and notable lattice contraction.

Contribution

The paper introduces hydroxide ion doping as a novel method to enhance Tc in LnFeAsO superconductors, achieving higher Tc and unique lattice changes.

Findings

Tc increased to 35 K with hydroxide doping

Hydrogen atoms confirmed by 1H-NMR measurements

Lattice parameters contracted beyond previous doping methods

Abstract

We report that the incorporation of hydroxide ions (OH)- significantly enhances the superconducting transition temperature (Tc) in the LnFeAsO-based superconductors (Ln1111: Ln = La, Ce and Pr). For La1111, Tc of the (OH)- incorporated sample synthesized using high-pressure technique becomes 35 K, which is higher by 7 K than the typical optimally-doped La1111 superconductors. Similar enhancement in Tc is also observed for Ce1111 and Pr1111. 1H-NMR measurement have confirmed the existence of hydrogen atoms in the samples. Accompanying the (OH)- incorporation, the lattice parameters are largely contracted, down to the values which have never been attained by any other dopings/substitutions.