Abstract
Problem Statement: Electrical and magnetoresistive properties of the Nd doped (La1-xNdx)0.5Ba0.5MnO3 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, TP shifted towards lower temperatures as Nd doping increased followed by decreasing of the activation energy (Ea), 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) 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.
Highlights
The discovery of colossal magnetoresistivity in mixed valent manganites has led to a resurgence of interest in this family of compounds
A large low-field MR capacity component has been observed in polycrystalline manganite samples, with a disruption in the crystalline order at the grain boundaries induces a local spin disorder[2,3]
Using Grain Boundaries (GB’s) to manipulate the magnetic behavior has been proven to be a simple method for enhancing the low-field sensitivity of these materials
Summary
The discovery of colossal magnetoresistivity in mixed valent manganites has led to a resurgence of interest in this family of compounds. On substituting trivalent La with a divalent ion such as Ca or Ba, one d electron is transferred out from Mn3+ to oxygen, so that La1-xBaxMnO3 for instance has a fraction (1-x) of the. Mn ions in the 3+state and fraction x in the 4+state These systems have technological importance such as in sensor application and increasing data storage by increasing in sensitivity of hard disk drive read heads[1]. Using Grain Boundaries (GB’s) to manipulate the magnetic behavior has been proven to be a simple method for enhancing the low-field sensitivity of these materials. Many of the observed effects are due to the strong connection between magnetism and the insulator to metal transition special to these systems.
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