Effect of Cr substitution on ferrimagnetic and ferroelectric properties of GaFeO3 epitaxial thin films

Abstract

To control the properties of multiferroic materials, substitution of magnetic elements is a useful technique. In this study, we fabricated GaCrxFe1−xO3 and Ga1−yCryFeO3 films by substituting Cr3+ (3d3) ions in GaFeO3 for magnetic Fe3+ (3d5) and nonmagnetic Ga3+ (d10) sites, respectively. The effect of the Cr substitution on the magnetic and dielectric properties was systematically investigated. The obtained GaCrxFe1−xO3 and Ga1−yCryFeO3 films (x ≤ 1/4 and y ≤ 1/2) simultaneously exhibit ferrimagnetism and ferroelectricity. For the GaCrxFe1−xO3 films, the magnetic transition temperature (TC) and magnetic anisotropy decrease with increasing x. On the other hand, for the Ga1−yCryFeO3 films, TC increases with increasing y. Unlike the GaFeO3 film, the Cr-substituted GFO films show a peak in the magnetization versus temperature curves and exhibit a sudden decrease in the coercive field near the peak, probably due to the formation of Fe3+–O–Cr3+ coupling which prefers to form ferromagnetic interactions in the antiferromagnetic Fe3+–O–Fe3+ networks. Furthermore, we found that the Cr-substituted GaFeO3 films show out-of-plane ferroelectricity at room temperature.