Dimensionality induced enhancement of ferromagnetic spin order and ferroelectric polarization in Ga doped α-Fe2O3 thin films

Abstract

The thin films of Ga doped hematite (α-Fe2O3) were grown on p-Si 〈111〉 substrate using Pulsed Laser Deposition technique. The as-grown films indicated crystalline peaks of rhombohedral structure. The films exhibited enhancement of ferromagnetic properties. The reduction of dimensionality of the materials in thin films (2D) has shown unusual magnetic spin order and exchange bias effect at temperatures < 70 K. The ferromagnetic parameters (magnetization, coercivity) showed dependence on composition, deposition conditions and heat treatment of the films. The as-grown films showed a good signature of ferroelectric polarization. The as-grown films of Fe1.8Ga0.2O3, having relatively large surface roughness, exhibited smaller magnetic moment in comparison to as-grown films of Fe1.6Ga0.4O3 with small surface roughness. The X-ray photoelectron spectroscopy measurements confirmed a chemically homogeneous state of high spin Fe3+ ions in as-grown films of Fe1.6Ga0.4O3 composition, whereas chemical state of Fe ions is consisting of the mixture of high spin Fe3+ and Fe2+ states in as-grown films of Fe1.8Ga0.2O3.