Tuning the Magnetic Ordering Temperature of Hexagonal Ferrites by Structural Distortion Control

TL;DR

This study demonstrates how atomic-scale structural distortions can enhance the magnetic ordering temperature in hexagonal ferrites, revealing new pathways for tuning magnetic properties through symmetry and lattice engineering.

Contribution

The paper uncovers the relationship between structural distortion and magnetic ordering temperature, predicting and experimentally confirming a record-high TN in hexagonal ScFeO3.

Findings

Larger structural distortion increases TN in hexagonal ferrites.

A near-linear relation exists between TN and the tolerance factor.

A power-law relation links TN and K3 distortion amplitude.

Abstract

To tune the magnetic properties of hexagonal ferrites, a family of magnetoelectric multiferroic materials, by atomic-scale structural engineering, we studied the effect of structural distortion on the magnetic ordering temperature (TN). Using the symmetry analysis, we show that unlike most antiferromagnetic rare-earth transition-metal perovskites, a larger structural distortion leads to a higher TN in hexagonal ferrites and manganites, because the K3 structural distortion induces the three-dimensional magnetic ordering, which is forbidden in the undistorted structure by symmetry. We also revealed a near-linear relation between TN and the tolerance factor and a power-law relation between TN and the K3 distortion amplitude. Following the analysis, a record-high TN (185 K) among hexagonal ferrites was predicted in hexagonal ScFeO3 and experimentally verified in epitaxially stabilized films. These results add to the paradigm of spin-lattice coupling in antiferromagnetic oxides and suggests further tunability of hexagonal ferrites if more lattice distortion can be achieved.