# Superconductivity at 48 K of heavily hydrogen-doped SmFeAsO epitaxial films grown by topotactic chemical reaction using CaH2

## TL;DR

This study reports the achievement of 48 K superconductivity in hydrogen-doped SmFeAsO epitaxial films, developed through pulsed laser deposition and a novel topotactic chemical reaction, confirming bulk superconductivity with potential for broad application.

## Contribution

It introduces a new method combining pulsed laser deposition and topotactic chemical reaction to create high-quality hydrogen-doped oxyhydride epitaxial films with high Tc.

## Key findings

- Superconductivity at 48 K achieved in hydrogen-doped SmFeAsO films.
- Maximum hydrogen concentration of ~0.35 confirmed.
- Bulk nature of superconductivity validated by magnetization measurements.

## Abstract

High-critical-temperature (Tc) superconductivity at 48 K is reported for hydrogen-doped SmFeAsO epitaxial films on MgO single-crystal substrates. The key processes are pulsed laser deposition to grow undoped SmFeAsO epitaxial films and subsequent topotactic chemical reaction using CaH2 powders under evacuated silica-glass ampule atmosphere. Based on this post-deposition thermal annealing treatment that we have developed, a maximum hydrogen concentration x = ~0.35 was realized in SmFeAs(O1-xHx). Disordered hydrogen-substitution at O sites is experimentally confirmed directly by atomic-scale microstructural observations. Magnetization measurement validates the bulk nature of the high-Tc superconductivity in the films. This method will become an effective and general method to fabricate various high-quality oxyhydride epitaxial films.

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Source: https://tomesphere.com/paper/1903.11819