Tuning of the ferromagnetic transition by impurity doping in Ru$Sr_2$EuCe$Cu_2$$O_z$

불순물 치환을 통한 Ru$Sr_2$EuCe$Cu_2$$O_z$ 계의 강자성 천이온도의 조절특성

We investigated the effects of impurity doping on the electrical transport and magnetic properties of TEX>$(Ru, Sn)(Sr, La)<_2$$EuCeCu_2$$O_{z}$ samples. We found that Sn substitution fur Ru causes a significant decrease of the volume fraction of ferromagnetic phase, as well as a decrease of the temperature where the ferromagnetic component is observed. La substitution for Sr leads to an increase of the magnetic ordering temperature with a moderate change of ferromagnetic component. The experimental results are discussed in conjunction with the structural data, transport properties and a possible change of oxygen content.