Ab initio investigation of the magnetic and ferroelectric properties of BaCuF4 under hydrostatic pressure

We present a first-principles investigation of the magnetic and ferroelectric properties of ${\mathrm{BaCuF}}₄$. Our calculations indicate that the magnetic topology is one-dimensional, with a N\'eel temperature smaller than 1 K, if existing. We also show that applying high-pressure values up to 40 GPa on ${\mathrm{BaCuF}}₄$ does not induce three-dimensional magnetic order. In addition, our calculations predict that the polar phase is destabilized under pressure. The first consequence is to reduce the energy barrier between $Cmc{2}₁$ polar and $Cmcm$ nonpolar phases, enhancing the ability to reverse the polarization. The second consequence is the disappearance of ferroelectricity above a critical pressure of 12.6 GPa.