LAUSR

Nanomagnets with giant magnetic anisotropy energy and long coherence time are desired for various technological innovations such as quantum information procession and storage. Based on the first-principles calculations and model analyses, we demonstrate that a single uranium atom substituting Al on the ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)$ surface may have high structural stability and large magnetic anisotropy energy up to 48 meV per uranium atom. As the magnetization resides in the localized $f$ shell and is not much involved in chemical bonding with neighbors, long coherence time up to $\ensuremath{\sim}1.6\phantom{\rule{0.16em}{0ex}}\mathrm{mS}$ can be achieved for the quantum spin states. These results suggest a different strategy for the search of ultrasmall magnetic units for diverse applications in the quantum information era.