Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr_2ScFeAsO_3

摘要

Additional charge carriers were introduced to the iron oxyarsenide Sr_2ScFeAsO_3 under a high-pressure condition, followed by measurements of electrical resistivity, the Hall coefficient, and magnetic susceptibility. The host compound Sr_2ScFeAsO_3 shows metallic conductivity down to ~200 K and turns to show a semiconducting-like conductivity accompanied by a positive magnetoresistance (22% at 70 kOe). Although the carrier density is comparable at 300 K (5.9 × 10~(21) 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 three 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.