Low temperature ferromagnetism, surface paramagnetism and exchange bias effect in nano-grained alpha-Fe1.4Ga0.6O3 oxide

TL;DR

This study reports the synthesis of alpha-Fe1.4Ga0.6O3 nano-grains exhibiting enhanced room temperature ferromagnetism, surface paramagnetism, and exchange bias effects, advancing the development of unconventional ferromagnetic materials.

Contribution

It introduces a novel nano-grained alpha-Fe1.4Ga0.6O3 compound with modified magnetic properties due to Ga substitution, including enhanced ferromagnetism and exchange bias effects.

Findings

Enhanced ferromagnetism confirmed by M"ossbauer spectroscopy.

Presence of exchange bias and surface paramagnetism at low temperatures.

Magnetic features are influenced by nano-grain size.

Abstract

The compound alpha-Fe1.4Ga0.6O3 has been prepared by mechanical alloying of alpha-Fe2O3 and Ga2O3 and subsequent heating of the mechanical alloyed samples in vacuum condition. Magnetic ordering of alpha-Fe2O3 has been modified by substitution of non-magnetic Ga atoms. The ferromagnetism in alpha-Fe1.4Ga0.6O3 is more soft and enhanced in comparison to alpha-Fe2O3. M\"ossbauer spectroscopy also confirmed enhanced ferromagnetic order in alpha-Fe1.4Ga0.6O3. The room temperature soft ferromagnetism by Ga substitution is interesting for designing alpha-Fe2O3 based unconventional ferromagnet, which is a great challenge to the materials scientists. The alpha-Fe1.4Ga0.6O3 samples also exhibited features of exchange bias, low temperature surface paramagnetism, and suppression of Morin transition. These features have been affected up to certain extent by the nano-sized grains of the samples.