Electrical and Magnetoresistive studies Nd doped on La-Ba-Mn-O3 Manganites for Low-field Sensor application

Abstract

Problem Statement: Electrical and magnetoresistive properties of the Nd doped (La_1-xNd_x)_0.5Ba_0.5MnO₃ type samples with 0 ≤ x ≤ 1.0 had been prepared using the solid state reaction. These materials are extensively studied by the substitution of rare-earth compound is to understand the nature of transport phenomena in each system. Approach: The samples were calcined at 900°C for 12 h, pelletized and sintered at 1300°C for 24 h. Electrical property had been determined by using standard four-point probe resistivity measurement within a temperature range of 30-300 K. The Magnetoresistance (MR) was measured using a conventional four terminal method with magnetic fields of H ≤ 1 T at 90, 100, 150, 200, 250, 270 and 300 K. Results: The metal-insulator transition temperature, T_P shifted towards lower temperatures as Nd doping increased followed by decreasing of the activation energy (E_a), The observed behavior had been explained on the basis of oxygen deficiency present in the samples. The electrical resistivity data were analyzed using various theoretical models and it had been concluded that the electrical resistivity data in the low temperature regime (T<Tp) can be explained using the equation ρ = ρ₀+ρ₂T²+ρ_4.5T^4.5, signifying the importance of the grain/ domain boundary, electron-electron and two magnon scattering processes. On the other hand, the high-temperature resisitivity data (T>Tp) were explained using variable range mechanism. All samples exhibit LFMR and HFMR regime, except x = 1 at higher temperature. Overall, MR drops slowly when temperature was increased. All doping concentration gives small variation in MR (~8.97-~63.49%). The highest MR value of 63.49% was observed at 150 K for the x = 1 sample. Conclusion: In this case, it showed that LFMR can be observed at a temperature 90 K. it provided a large variation of LFMR in range of ~100-~160% MR/Tesla. These values were very sensitive for low-field application and therefore it’s also acceptable as a requirement for a sensing element.