Superconducting transition temperatures in the electronic and magnetic phase diagrams of Sr2VFeAsO3-delta, a superconductor

TL;DR

This study investigates the magnetic phases and superconducting transition temperatures in Sr2VFeAsO3-delta, revealing how vanadium valence states influence superconductivity and identifying two Tc maxima related to magnetic phase boundaries.

Contribution

It provides detailed phase diagrams of Sr2VFeAsO3-delta, highlighting the role of vanadium magnetic phases in superconductivity, which is a novel insight into iron-based superconductor mechanisms.

Findings

Superconductivity occurs in delta range 0.031 to 0.145.

Two Tc maxima at delta = 0.073 and 0.145.

Vanadium magnetic phases significantly influence Tc.

Abstract

We elucidate the magnetic phases and superconducting transition temperatures (Tc) in Sr2VFeAsO3-delta (21113V), an iron-based superconductor with a thick-blocking layer fabricated from a perovskite-related transition metal oxide. At low temperatures (T < 37.1 K), 21113V exhibited a superconducting phase in the range 0.031 =< delta =< 0.145 and an antiferromagnetic (AFM) iron sublattice in the range 0.267 =< delta =< 0.664. Mixed-valent vanadium exhibited a dominant AFM phase in 0.031 =< delta =< 0.088, and a partial ferrimagnetic (Ferri.) phase in the range 0.124 =< delta =< 0.664. The Ferri. phase was the most dominant at a delta value of 0.267, showing an AFM phase of Fe at T < 20 K. Increasing the spontaneous magnetic moments reduced the magnetic shielding volume fraction due to the superconducting phase. This result was attributed to the magnetic phase of vanadium, which dominates the superconductivity of Fe in 21113V. The Tc-delta curve showed two maxima. The smaller and larger of Tc maxima occurred at delta = 0.073 and delta = 0.145, respectively; the latter resides on the phase boundary between AFM and the partial Ferri. phases of vanadium. 21113V is a useful platform for verifing new mechanisms of Tc enhancement in iron-based superconductors.