Impact of sintering temperature on the physical properties of the superconducting ferromagnet: RuSr2Eu1.5Ce0.5Cu2O10

We report the influence of the sintering temperature on the electromagnetic behavior for the RuSr2Eu1.5Ce0.5Cu2O10 material, in which superconductivity and ferromagnetism coexist. The inadequate heat treatment results in the coexistence of the secondary Ru-1212 phase along with the dominant Ru-1222 phase. The presence of two phases leads to the magnetic superposition of the signals from both phases, which results in the observation of a small peak around 120–130 K. In the pure Ru-1222 no such magnetic anomaly is observed. In addition, the impure samples exhibit a double step superconductivity transition. In the normal state, these impure samples exhibit a semiconductinglike behavior of the resistivity. In contrast, the pure Ru-1222 sample with much larger, well connected grains has a single step resistivity transition, as well as a metalliclike behavior in the normal state. Our work sends a strong message that only high quality, phase pure samples can be chosen for the investigation of the complex behavior in the Ru system.