Dielectric, magnetic, and magnetotransport properties in Sr doped two-dimensional RE2CoO4 (RE=Pr,Eu) compounds

Abstract

In this work, we report on the studies of dielectric, magnetic, and magnetotransport properties of Sr doped RE2−xSrxCoO4 (RE=Pr or Eu, x=0.25–1.5). These compounds were systematically studied in terms of structure, magnetic, magnetotransport, and dielectric constant measurements. Rietveld refinement indicated that these compounds crystallized in K2NiF4-type structure with space group I4∕mmm. Lattice parameters increase with Sr doping level. The system changes from paramagnetic to ferromagnetic with increasing Sr doping level and finally becomes ferromagnetic with TC of 230K for Pr0.75Sr1.25CoO4 and EuSrCoO4, respectively. The temperature dependence of resistivity indicates that both systems change from semiconductive to metallic with Sr doping. The magnetoresistance (MR) value of 10% at 5K and 8T is found for the EuSrCoO4 compound. Large dielectric constants with values of above 2000 were observed in low frequencies for samples with x around 1 for Pr based compounds.