Enhanced ferromagnetic transition temperature in NdOxDy epitaxial thin films

We investigated the electrical transport properties and magnetic properties of oxygen-containing fluorite-type neodymium dideuteride, $\mathrm{Nd}{\mathrm{O}}_{x}{\mathrm{D}}_{y}$, epitaxial thin films $(0.05\ensuremath{\le}x\ensuremath{\le}1.4)$ grown on $\mathrm{Ca}{\mathrm{F}}_{2}(111)$ substrate by a pulsed laser deposition technique. The $\mathrm{Nd}{\mathrm{O}}_{x}{\mathrm{D}}_{y}$ thin films with $x\ensuremath{\le}0.3$ were crystallized in a pure fluorite phase, while the films with $x\ensuremath{\ge}0.6$ were mixtures composed of fluorite and hexagonal $\mathrm{N}{\mathrm{d}}_{2}{\mathrm{O}}_{3}$-type phases. In the fluorite phase, ferromagnetism was observed from a magnetization loop and anomalous Hall effect. The films with $x<1.4$ showed metallic transport properties with an abrupt drop of resistivity below Curie temperature ${T}_{C}$. With increasing $x$, ${T}_{C}$ was raised to 10.0 K, which was higher than that of $\mathrm{Nd}{\mathrm{H}}_{2+x}$ with comparable carrier density.