Magnetic and electrical properties and carrier doping effects on the Fe-based host compound Sr4Sc2Fe2As2O6

TL;DR

This study investigates how doping affects the electrical and magnetic properties of Sr4Sc2Fe2As2O6, revealing significant changes in conductivity and magnetic behavior but no superconductivity down to 2 K.

Contribution

It provides new insights into carrier doping effects on Fe-based compounds, highlighting the suppression of superconductivity and magnetic ordering mechanisms.

Findings

Metallic to semiconducting transition around 200 K

Carrier density decreases by over 3 orders of magnitude upon cooling

No superconductivity observed down to 2 K

Abstract

Additional charge carriers were introduced to the iron oxyarsenide Sr4Sc2Fe2As2O6 under a high-pressure condition, followed by measurements of electrical resistivity, Hall coefficient, and magnetic susceptibility. The host compound Sr4Sc2Fe2As2O6 shows metallic conductivity down to ~200 K and turns to show a semiconducting-like conductivity accompanied by a positive magneto-resistance (22% at 70 kOe). Although the carrier density is comparable at 300 K (5.9x1021 cm-3) with that of the other Fe-based superconductors, no superconductivity appears down to 2 K. This is primarily because the net carrier density decreases over 3 orders of magnitude on cooling and additionally a possible magnetic order at ~120 K prevents carriers from pairing. The properties were altered largely by introducing the additional carriers.