Synthesis and physical characterization of superconductivity–magnetism crossover compound RuSr2EuCeCu2O10−δ

We carefully studied the nonsuperconducting sample of the magneto-superconducting RuSr2(Eu1−xCex)Cu2O10−δ series with composition RuSr2EuCeCu2O10−δ. This compound seems to exhibit a complex magnetic state as revealed by host of techniques like resistivity, thermopower, magnetic susceptibility, and MR measurements. The studied compound exhibited ferromagnetic like M(H) loops at 5, 20, and 50 K, and semiconductor like electrical conduction down to 5 K, with −MR7 T of up to 4% at low temperatures. The −MR7 T decreases fast above 150 K and monotonically becomes close to zero above say 230 K. Below, 150 K −MR7 T decreases to around 3% monotonically down to 75 K, with further increase to 4% at around 30 K and lastly having a slight decrease below this temperature. The thermopower S(T) behavior closely followed the −MR7 T steps in terms of d(S/T)/dT slopes. Further, both MR7 T steps and d(S/T)/dT slopes are found in close vicinity to various magnetic ordering temperatures (Tmag) of this compound.