Interplay of 4f-3d Magnetism and Ferroelectricity in DyFeO3

TL;DR

This study reveals that DyFeO3 exhibits intrinsic ferroelectricity in its weak ferromagnetic state, driven by 4f-3d magnetic interactions, without external magnetic fields, highlighting the interplay between magnetism and ferroelectricity.

Contribution

It demonstrates the intrinsic ferroelectricity in DyFeO3's weak ferromagnetic state and elucidates the role of Dy-Fe magnetic interactions in this phenomenon.

Findings

Ferroelectricity exists without external magnetic field in the weak ferromagnetic state.

Hyperfine field deviations indicate Dy-Fe magnetic interactions influence ferroelectricity.

Magnetic interactions between Dy(4f) and Fe(3d) are correlated with ferroelectric behavior.

Abstract

DyFeO3 exhibits a weak ferromagnetism (TNFe ~ 645 K) that disappears below a spin-reorientation (Morin) transition at TSRFe ~ 50 K. It is also known that applied magnetic field induces ferroelectricity at the magnetic ordering temperature of Dy-ions (TNDy ~ 4.5 K). Here, we show that the ferroelectricity exists in the weak ferromagnetic state (TSRFe < T < TN,C) without applying magnetic field, indicating the crucial role of weak ferromagnetism in inducing ferroelectricity. 57Fe M\"ossbauer studies show that hyperfine field (Bhf) deviates from mean field-like behaviour that is observed in the weak ferromagnetic state and decreases below the onset of spin-reorientation transition (80 K), implying that the Bhf above TSR had additional contribution from Dy-ions due to induced magnetization by the weak ferromagnetic moment of Fe-sublattice and below TSR, this contribution decreases due to collinear ordering of Fe-sublattice. These results clearly demonstrate the presence of magnetic interactions between Dy(4f) and Fe(3d) and their correlation with ferroelectricity in the weak ferromagnetic state of DyFeO3.