Hexagonal phase stabilization and magnetic orders of multiferroic Lu$_{1-x}$Sc$_x$FeO$_3$

TL;DR

This study demonstrates that partial Sc substitution stabilizes the hexagonal phase of bulk LuFeO$_3$, preserving its multiferroic properties and revealing high-temperature magnetic ordering and magnetoelectric coupling.

Contribution

First-principles calculations show hexagonal LuFeO$_3$ can be stabilized in bulk by Sc substitution, maintaining multiferroic properties, and experimental characterization reveals high-temperature magnetic order and magnetoelectric effects.

Findings

Hexagonal phase stabilized in bulk LuFeO$_3$ by Sc substitution.

High-temperature magnetic anomaly around 425-445 K.

Magnetoelectric response observed at low temperatures.

Abstract

Hexagonal LuFeO$_3$ has drawn a lot of research attention due to its contentious room-temperature multiferroicity. Due to the unstability of hexagonal phase in the bulk form, most experimental studies focused on LuFeO$_3$ thin films which can be stabilized by strain using proper substrates. Here we report on the hexagonal phase stabilization, magnetism, and magnetoelectric coupling of bulk LuFeO$_3$ by partial Sc-substitution of Lu. First, our first-principles calculations show that the hexagonal structure can be stabilized by partial Sc substitution, while the multiferroic properties including the noncollinear magnetic order and geometric ferroelectricity remain robustly unaffected. Therefore, Lu$_{1-x}$Sc$_x$FeO$_3$ can act as a platform to check the multiferroicity of LuFeO$_3$ and related materials in the bulk form. Second, the magnetic characterizations on bulk Lu$_{1-x}$Sc$_x$FeO$_3$ demonstrate a magnetic anomaly (probable antiferromagnetic ordering) above room temperature, $\sim425-445$ K, followed by magnetic transitions in low temperatures ($\sim167-172$ K). In addition, a magnetoelectric response is observed in the low temperature region. Our study provides useful information on the multiferroic physics of hexagonal $R$FeO$_3$ and related systems.