Near Room-Temperature Magnetism and Enhanced Magnetic Moments in Multiferroic (LuFeO$_{3})_{\mathrm{m}}$/(LuFe$_{2}$O$_{4})_{\mathrm{n}}$ Superlattices

The development of room-temperature multiferroics is necessary to realize the potential of these materials in low-power energy, memory, and logic applications. Currently, there are only four potential single-phase multiferroics that exist at room-temperature, all of which have either antiferromagnetic or weakly ferromagnetic magnetic orderings. Here, we report on the magnetic properties of epitaxially grown superlattices composed of the ferroelectric, weakly ferromagnetic $h$-LuFeO$_{3}$ and the paraelectric, ferrimagnetic LuFe$_{2}$O$_{4}$. By inserting layers of $h$-LuFeO$_{3}$ ($T_{\mathrm{N}} = $147 K) into LuFe$_{2}$O$_{4}$, we increase $T_{\mathrm{C}}$ from 219 K for single-phase LuFe$_{\mathrm{2}}$O$_{4}$ to 270 K for (LuFeO$_{3}$)$_{7}$/(LuFe$_{2}$O$_{4}$)$_{1}$. Additionally, while the magnetic moment on the LuFe$_{2}$O$_{4}$ layers remains constant for $m$/($m+$2$n)$ \textless 0.5, it increases rapidly for $m$/($m+$2$n)$ \textgreater 0.5, resulting in magnetic moments orders of magnitude larger than the weak ferromagnetic room-temperature multiferroics. We will discuss the potential mechanisms for these enhanced transition temperatures and magnetic moments and the potential to increase $T_{\mathrm{C}}$ to above room temperature.