Impact of sintering temperature on the physical properties of the superconducting ferromagnet: RuSr_2Eu_(1.5)Ce_(0.5)Cu_2O_(10)

摘要

We report the influence of the sintering temperature on the electromagnetic behavior for the RuSr_2Eu_(1.5)Ce_(0.5)Cu_2O_(10) 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.