Observation of interfacial magnetic interaction in Eu-doped BiFeO3 and YMnO3 nanocomposites

Abstract

The results of structural and magnetic properties of (1-x)Bi0.96Eu0.04FeO3-(x)YMnO3 (x = 0.0,0.25,0.50,0.75,1) nanocomposites, synthesized using physical mixing method are presented in this work. The Eu doped bismuth ferrite and yttrium manganite nanoparticles are synthesized separately and then physically mixed using hydrothermal method. The physical mixing of the parent materials helps to retain the properties of both the materials in the nanocomposites. XRD patterns show the presence of both phases (R3c and P63cm) in the nanocomposites, without any structural distortion or presence of other intermediate phases. Morphological analysis of the samples is done using FESEM and HRTEM techniques. The FESEM results show that the particles in the parent as well as nanocomposites are irregularly distributed with agglomeration of particles in Eu doped BiFeO3 and the nanocomposite (BY-50). The interplanar distances corresponding to crystal planes of both phases are calculated for BY-50 nanocomposite from the HRTEM results. Chemical state analysis of BY-50, using XPS confirms the formation of nanocomposite. Multiple valence states for Fe (Fe2+ and Fe3+) and Mn (Mn2+, Mn3+ and Mn4+) are formed as a result of charge compensation phenomenon. The dominant Fe3+ and Mn3+ plays an important role in the magnetic properties of nanocomposites. Magnetic studies on the parent as well as the nanocomposites are done using room-temperature VSM. The M−H loops show wasp-waisted nature with the presence of weak ferromagnetism along with anti-ferromagnetic or paramagnetic ordering. The constricted nature of loops has been confirmed using ΔH (loop-width) versus M (magnetization) loops. The addition of YMnO3 in the nanocomposites slightly increases the maximum magnetization from 0.149 emu/g for Eu doped BiFeO3 nanoparticles to 0.364 emu/g for BY-75 nanocomposites. The maximum magnetization in the nanocomposites increases because of the constructive alignment of the spins at the interface. The presence of interfacial magnetic interaction in the samples has been corroborated through room-temperature X-band ESR analysis.