Anisotropic Magnetodielectric Coupling in Layered Antiferromagnetic FePS$_3$

TL;DR

This study reveals anisotropic magnetodielectric coupling in layered FePS$_3$, linking magnetic ordering to dielectric behavior and suggesting potential for spintronic applications through control of magnetic anisotropy.

Contribution

It demonstrates the anisotropic magnetodielectric effect in FePS$_3$ and connects it to magnetic anisotropy and spin-phonon interactions, providing insights into magnetic control of dielectric properties.

Findings

Dielectric response shows frequency dependence above T_N along c-axis.

Atypical dielectric anomaly occurs below 40 K, linked to magnetic susceptibility.

Magnetodielectric response varies with in-plane and out-of-plane orientations.

Abstract

We report anisotropic magnetodielectric (MD) coupling in layered van der Waals (vdW) antiferromagnetic (AFM) FePS$_3$ (N\'eel temperature $T_{\mathrm{N}}$ $\sim$ 120K) with perpendicular anisotropy. Above $T_N$, while dielectric response function along \textit{c}-axis shows frequency dependent relaxations, in-plane data is frequency independent and reveals a deviation from phonon-anharmonicity in the ordered state, thereby implying a connection to spin-phonon coupling known to be indicative of onset of magnetic ordering. At low temperature (below 40 K), atypical anomaly in the dielectric constant is corroborated with temperature dependent DC and AC susceptibility. The magnetodielectric response across this anomaly differs significantly for both, in-plane and out-of-plane cases. We have explained this in terms of preferential orientation of magnetic AFM-z alignment, implied by the in-plane structural anisotropy as confirmed by \textit{ab-initio} calculations. Controlling relative strength of magnetodielectric coupling with magnetic anisotropy opens up a strategy for tracking subtle modifications of structure, such as in-plane anisotropy, with potential application to spintronic technologies.