Superconductivity in New Iron Pnictide Oxide (Fe2As2)(Sr4(Mg,Ti)2O6)

TL;DR

This paper reports the discovery of a new iron pnictide oxide superconductor with a Tc above 35 K, highlighting the effects of Co substitution and high pressure on its superconducting properties.

Contribution

The study introduces a novel iron pnictide oxide superconductor with higher Tc and explores how chemical substitution and pressure enhance its superconductivity.

Findings

Superconductor with Tc onset ~26 K in Co-doped samples.

Higher Tc (>35 K) in Co-free, Ti-rich samples.

Tc further increased under high pressure to ~43 K.

Abstract

We have discovered a new iron pnictide oxide superconductor (Fe2As2)(Sr4(Mg,Ti)2O6). This material is isostructual with (Fe2As2)(Sr4M2O6) (M = Sc, Cr, V), which were found in previous studies. The structure of this compound is tetragonal with a space group of P4/nmm and consists of the anti-fluorite type FeAs layer and perovskite-type block layer. The lattice constants are a = 3.935 A and c = 15.952 A for (Fe2As2)(Sr4MgTiO6). Bulk superconductivity with Tc(onset) of ~26 K was observed for a partially Co substituted sample. Moreover, Co-free and Ti-rich samples exhibited higher Tc(onset)'s above 35 K, which were further enhanced by applying high pressures up to ~43 K.