Hole-doped manganites \({\text{La}}_{\left(0.6-x\right)}{\text{Ca}}_{x}{\text{Sm}}_{0.1}{\text{Ba}}_{0.3}{\text{MnO}}_{3}\) (with \(x=0.0\) and 0.1) were synthesized using a solid-state reaction method. The structural, microstructural, electrical transport, magnetotransport, and temperature coefficient of resistance (TCR) properties were thoroughly investigated. X-ray diffraction (XRD) analysis revealed that both compounds crystallized in an orthorhombic structure with the Imma space group, with no secondary phases detected. The Ca-doped sample exhibited significantly smaller and more homogeneous grains compared to the undoped sample. Resistivity measurements showed a metal–insulator transition around \(221 K\) , with the transition temperature shifting to lower values upon Ca-doping. Magnetoresistance (MR) values at low temperatures were substantial, reaching 23.37% for the undoped sample and \(23.7\%\) for the Ca-doped sample at \(290 K\) . The temperature dependence of resistivity exhibited both intrinsic and extrinsic contributions to magnetoresistance (MR), with a peak MR of 23.7% for the Ca-doped sample and \(23.37\%\) for the undoped one at low temperatures. The TCR curve showed a peak of \(1.78 \%{K}^{-1}\) at room temperature, indicating significant temperature-dependent resistance changes. Low-temperature resistivity was described with a combination of residual resistivity, weak localization, and electron–electron interactions, whereas the high-temperature behavior is well described by adiabatic small polaron hopping. These results bring out the complexity in the interrelation between structural changes and magnetotransport properties and emphasize the role of Ca-doping in tuning electrical and magnetoresistive properties in manganite perovskite.
