Critical magnetic inhomogeneities and crossover electrical transport properties in La0.4Bi0.6Mn0.99Ga0.01O3 manganite

The polycrystalline compound La0.4Bi0.6Mn0.99Ga0.01O3 has been studied for its interesting structural, magnetic and electrical transport properties. The compound has been synthesized using nitrate reaction route with the incorporation of controllable temperature cycling method. The phase purity of the studied compound has been verified from the X-ray diffraction and Reitveld refinement technique/analysis. The microstructural studies of the synthesized compound suggest proper crystalline shapes and elemental confirmation of the composition. The magnetization measurements carried out on the studied compound reveal that at low temperature, the magnetic spins exhibit glassy behavior and near phase transition temperature the inhomogeneity due to the critical frustrations. Further from the AC susceptibility measurements the low temperature magnetic spin interaction is found to be a manifestation of re-entrant spin glass like behavior, and from critical analysis, the magnetic inhomogeneity at phase transitions has been evidenced. The transport properties from the conductivity measurements carried out on the studied compound are understood based on the polaronic hopping model. Further at temperatures greater than the Debye temperature, the polaronic conduction follows small polaronic hopping mechanism and at temperatures less than the Debye temperature the polaronic conduction crossover to Mott’s variable range hopping mechanism. The magneto-conductivity measurements studied for the compound reveal the quadratic dependencies above the magnetic critical temperatures, where scattering mechanism is due to the phonon–polaron interactions.