Contrasting Magnetic Behaviors in Rhodium‐ and Ruthenium‐Doped Cubic Perovskite SrFeO₃: Nearly Ferromagnetic Metal versus Spin‐Glass Insulator

Abstract

The effects of Rh and Ru doping for SrFeO 3 , ah elimagnetic metal with ac ubic perovskites tructure,a re studied by magnetic and resistivity measurements.A lthough SrRhO 3 is aparamagnetic metal and SrRuO 3 is aferromagnetic one,t he Rh doping induces an early ferromagnetic metallic state,w hereas the Ru doping induces as pin-glass insulating state.M çssbauer measurements evidence am arked difference between SrFe 0.8 Rh 0.2 O 3 and SrFe 0.8 Ru 0.2 O 3 in the formal valences of Fe,w hicha re estimated to be 4 + and 3.75 + , respectively.T he contrasting magnetic behaviors of Rh-and Ru-doped SrFeO 3 are discussed in terms of the subtle balance between the double-exchange ferromagnetism and the superexchange antiferromagnetism.