Creation and modulation of ferromagnetism in antiferromagnetic hematite nanoplates

Abstract

Hematite is one of the most abundant oxides on the Earth, but the absence of macroscopic magnetism due to its inherent antiferromagnetic (AFM) property greatly restricts its applications. Here we demonstrate that significant ferromagnetism can be created and controlled in delicately designed hematite nanoplates with {001} planes, which were synthesized by a surfactant-free supersaturation-controlled method. We obtain a high magnetization of 14.14 emu g⁻¹ at room temperature, much higher than that reported in the literature. Meanwhile, the magnetization of α-Fe₂O₃ is dependent on the thickness of the nanoplates. It is revealed that the ferromagnetism arises from the uncompensated Fe moments on the {001} surface. This approach and mechanism could be extended to other AFM materials to enhance magnetization therein.