Pressure-induced large enhancement of Néel temperature and electric polarization in the hexagonal multiferroic Lu0.5Sc0.5Fe

Hexagonal ferrites ($h\text{\ensuremath{-}}R\mathrm{Fe}{\mathrm{O}}_{3}$) have attracted great attention for their high ferroelectric transition temperature, strong magnetoelectric couplings, and tunable N\'eel temperature (${T}_{N}$) and electric polarization. While introducing structural distortion has been previously found to be effective to raise ${T}_{N}$ and polarization in $h\text{\ensuremath{-}}R\mathrm{Fe}{\mathrm{O}}_{3}$, it is generally difficult to create sizable structural distortion by common approaches including substrate-induced epitaxial strain and chemical doping. Here, we use high-pressure x-ray-diffraction measurements to show that pressure can generate large structural distortion and R-layer displacement of $h\text{\ensuremath{-}}R\mathrm{Fe}{\mathrm{O}}_{3}$, resulting with dramatically enhancement of polarization and ${T}_{N}$. Density-functional theory calculations reveal that the enlarged $c/a$ ratio results in an \ensuremath{\sim}70 K increase of ${T}_{N}$ along with a significant enhancement of ferroelectric polarization. Our results suggest that pressure is effective to tune structural distortions and related multiferroicity of the $h\text{\ensuremath{-}}R\mathrm{Fe}{\mathrm{O}}_{3}$ system, making $h\text{\ensuremath{-}}R\mathrm{Fe}{\mathrm{O}}_{3}$ a promising material for spintronic applications.