Effect of hole doping and antiferromagnetic coupling on the itinerant ferromagnetism of SrRuO3 through Cu substitution at Ru site

Abstract Systematic studies on the structural, transport and magnetic properties of SrRu 1− x Cu x O 3 ( x = 0.0 – 0.2 ) compounds have been performed. SrRu 0.8 Cu 0.2 O 3 shows a tetragonal structure unlike the other compositions which exhibit a pseudo-cubic structure. Low temperature powder X-ray diffraction data of SrRu 0.8 Cu 0.2 O 3 collected at a synchrotron beam line reveals that the tetragonal structure is stable down to 8 K. Ferromagnetic transition temperatures ( T c ) are significantly reduced from 160 to 34 K with Cu doping. All the compositions exhibit irreversibilities in M ZFC ( T ) and M FC ( T ) curves ascribable to the presence of domain structures. Magnetic susceptibility measurements show that the copper ions are anti-ferromagnetically coupled for concentrations higher than x = 0.16 . The antiparallel arrangement of Ru 5+ ions with its neighboring cations also contributes to the large reduction in the observed magnetic moment. X-ray photoemission spectroscopy measurements show evidence for both tetravalent and pentavalent Ru ions while copper is in a divalent state. We conclude from our resistivity data that Cu 2+ substitution promotes a polaronic type of conductivity.