| The study of ruthenium-based oxides which is a type of transition-metal oxides is always a highlight of research on condensed matter physics, and is used to explore the property of 4d electron system due to the existence of 4d electrons in Ru. Sr2RuO4 and SrRuO3 belong to Ruddlesden-Popper series Srn+1RunO3n+1(n=1, 2, 3…), but they show distinct physical properties such as the discovery of superconductivity near 1 K in Sr2RuO4 and the transition of ferromagnetism to paramagnetism near 160K in SrRuO3. It is found that the physical property of BaRuO3 is changed by ordered or disordered doping. There is no a definite conclusion on the cause of how the ferromagnetic transition temperature is changed in doped SrRuO3 so far. So we try to get more information through double-doping method. At the same time, we attempt to explore the physical property of BaRu1-xCrxO3 due to the dramatic change of magnetism of SrRu1-xCrxO3.We give a brief overview on the properties of SrRuO3 and BaRuO3, which include the crystal structure, conductivity, magnetism, pseudogap, specific heat and the doping effect. It is our goal to investigate the doping effect in SrRuO3 and BaRuO3. There is some interesting phenomenon in double-doped SrRuO3: the ordered moment is reduced due to the antiferromagnetic coupling of Ru and Cr, and the coercive field is increased due to the enhanced pinning effect on the domain walls induced by the disorder brought about by doping. In contrast, there is no dramatic change of magnetism of BaRu1-xCrxO3 and the conductivity and specific heat is changed due to the disorder brought about by doping, which is different from that of SrRu1-xCrxO3. It is maybe only a role of defect for the substitution of Ru for Cr in BaRuO3.The magnetism of BaRuO3 with 9R phase is intrinsic, which is determined by the crystal structure and has little to do with oxygen content after annealing in oxygen. |
