Tuning the magnetic and magnetotransport properties of Pr_0.8Sr_0.2MnO₃ manganites through Bi-doping

Magnetic and magneto-transport properties of Pr_0.8−xBi_xSr_0.2MnO₃ (x = 0, 0.05 and 0.1) compounds were investigated. All samples exhibited a second-order paramagnetic-ferromagnetic transition with the decrease in temperature. The Curie temperature decreased from 210 to 140 K with the Bi-doping content. The electrical resistivity of the parent sample was described by the phenomenological percolation model, which is based on the phase segregation. The metallic character observed in the pristine sample was reduced, and then entirely suppressed by 10% of Bi. The resistivity data for doped samples were described using Mott's variable range hopping model at high temperatures and by electron-electron interaction and inelastic scattering mechanisms at low temperatures. A Colossal magnetoresistance (MR) was observed in the studied samples. The parent sample illustrated the predominance of intrinsic MR but in doped compounds, MR curves revealed the coexistence of intrinsic and extrinsic contributions. Bi-doping was found to enhance the extrinsic MR in Pr_0.8−xBi_xSr_0.2MnO₃ (0 ≤ x ≤ 0.1) samples. (paper)