Tuning of magnetic properties and multiferroic nature: case study of cobalt-doped NdFeO3

Abstract

Nanocrystalline NdFe1-xCoxO3 (0 ≤ x ≤ 0.4) samples have been synthesized by a sol–gel auto-combustion route. Rietveld refinement of x-ray diffraction patterns of the samples confirms the single-phase orthorhombic structure with space group Pbnm- $${D}_{2h}^{16}$$ . Williamson–Hall analysis is carried out to evaluate the average crystallite size and lattice strain. Raman scattering spectra indicate compressive strain with blueshift in doped samples. The particles that appeared in FESEM micrographs are found to be approximately spherical in shape, and the average size lies in the range of 32–58 nm. Pore radius and surface area of the powders have been determined by BET method. The room-temperature magnetic studies reveal a strong antiferromagnetic behavior with weak ferromagnetism due to Dzyaloshinskii–Moriya (D–M) exchange interaction mechanism. Cobalt doping enhances the magnitude of magnetization in NdFeO3 sample. The maximum magnetization (Mmax) is achieved to be 1.209 emu/g for 10% cobalt-doped sample. The deconvolution of M–H loop in ferromagnetic and antiferromagnetic parts has been performed. Room-temperature polarization–electric field (P–E) loops at different applied electric fields suggest the typical ferroelectric nature of all the samples. Maximum polarization (Pm) is found to be 1.09 μC/cm2 for x = 0.2 sample at 50 kV field. Temperature-dependent P–E loops exhibit an increase in coercive field (Ec) and polarization (P) with the increase in temperature, and this behavior indicates the growth in energy barrier for domain reorientation. Pore radius, density, and particle size have been correlated with magnetic and electrical properties of the nanocrystalline samples.