Dataset: Improper Ferroelectricity at the Monolayer Limit

Raw data supporting the study on ultrathin improper ferroelectricity in hexagonal LuFeO₃ (h-LuFeO₃) films, as described in the associated publication (https://doi.org/10.48550/arXiv.2503.06214). This includes raw and processed experimental data characterizing the structural, ferroelectric, and thermal properties of 0.75-unit-cell-thick h-LuFeO₃ films grown on SrCo₂Ru₄O₁₁ electrodes with a monolayer bridging layer. The dataset contains high-resolution microscopy images, X-ray diffraction (XRD) patterns, polarization–electric field (P–E) hysteresis loops, temperature-dependent measurements, and supporting computational data. These data demonstrate the persistence of ferroelectricity and high Curie temperature in the ultrathin limit, confirming the absence of a critical thickness for improper ferroelectrics.