Magnetic and electrical properties of Ti-substituted lanthanum bismuth manganites

We are reporting the influence of non-magnetic Ti ions on magnetic, electrical, magneto-transport, and dielectric responses in polycrystalline ferromagnetic insulating samples \( {\text{La}}_{ 0. 4} {\text{Bi}}_{ 0. 6} {\text{Mn}}_{{ 1 { - }x}} {\text{Ti}}_{x} {\text{O}}_{ 3} \) (x = 0.05 and 0.10) synthesized by solid-state route method. Powder X-ray diffraction analysis reveals that the samples crystallize in tetragonal structure indexed to I4/mcm space group. Scanning electron micrographs suggest that the increase in Ti substitution inhibits grain growth process leading to decrease in grain size. The characteristic magnetic dilution with increase in x is evident due to the non-magnetic nature of the Ti ions. Also, in magnetization curve, the observed glassy behavior restricts the long-range magnetic spin interactions in the broader temperatures range. The electrical resistivity measurements exhibited semiconducting nature throughout the measured temperature range (110–300 K) without metal-semiconductor phase transition. The magneto-transport behavior in the paramagnetic region (for T > 150 K) follows \( \left[ {{\text{MR}}\sim \frac{\Delta \rho }{{\rho \left( {0T} \right)}}} \right] \propto H^{n} \) relation, giving possible correlation between electrical and magnetic properties. Resistivity data at low temperature region suggest that the conduction is due to the hopping of charge carrier, satisfying SE-VRH mechanism. However, the resistivity data at high-temperature regime suggest the localization of small polarons. The large dielectric responses achieved with multiple relaxations are understood due to extrinsic and intrinsic properties. Complex impedance spectrums have been analyzed using equivalent circuits to determine different contributions responsible for the relaxation process with Ti substitution.