Evolution of electronic transport in superconducting thin films of Pr_1.84Ce_0.16CuO_4+δ upon substitution of Ni at Cu site

The electronic properties in cuprates are primarily dominated by their CuO₂ layers and hence, the substitution of Cu by any other 3d transition metal can serve as a strong probe to understand their origin and high-T_c superconductivity. Previous studies on electron-doped cuprates show remarkable transformations of their electronic properties by attempting partial substitution of Cu by 3d transition metals in single crystals and polycrystals. However, these previous approaches suffer from randomly fluctuating Ce and O contents from sample to sample, which also strongly influence electronic transport. In our study, we have carried out a systematic investigation of the electronic transport in the electron-doped cuprate system of Pr_1.84Ce_0.16Cu_1-yNi_yO_4+δ as a function of Ni substitution at Cu site using thin films made by pulsed laser deposition, offering precise control over stoichiometry. The films are characterized using X-ray diffraction to ensure high-quality epitaxial thin films. We rely on electrical resistivity (ρ) and Hall coefficient (R_H) measurements to assess the impact of Ni doping. Due to the disorder introduced by Ni, we observe a clear suppression of T_c, a rise in residual ρ_o, emergence of linear-in-T ρ, and unexpectedly, R_H that shifts towards positive values. Our results indicate how a substitution of Ni at Cu site causes suppression of superconductivity and provide a deep insight into the effects of different sources of disorder, scattering and charge carrier dynamics.