Tunable Magnetic Phase Change and Polaronic Hopping Conductions in (Sm, Mn) Half Doped LaFeO3 Nanoparticle

Abstract

Effect of simultaneous Sm and Mn substitutions around half-doping level on the structural, magnetic and low temperature electronic behaviour of LaFeO₃ nanoparticle is extensively studied. The SXRD and FESEM data shows a single-phase nanoparticle of size 33?nm. A drastic magnetic phase change with a low temperature non-ergodic phase is seen compared to the parent LaFeO₃ (G-type antiferromagnetic) and this typical behaviour stems from the facts that, simultaneous presence of Sm and Mn alters the Fe crystal environment as well as its multiplicity which leads to improved exchange interactions among different ions. The doped nanoparticle shows a colossal dielectric response. Impedance, modulus spectra and ac conductivity analysis are used to find the conduction process involved in the system and it is related to the hopping conduction through grain and grain boundary resistances. The possibility of the polaronic part may arise from the interactions among mixed-valence state of Fe (Fe³⁺/Fe²⁺), Mn (Mn³⁺/Mn²⁺) and from the oxygen vacancies. Moreover, the ac-electrical conductivity is analysed using Jonscher’s double-power law and Jump relaxation model.