Room-Temperature Ferromagnetic Ultrathin α-MoO:Te Nanoflakes.

We materialized room-temperature ferromagnetism in ultrathin α-MoO:Te nanoflakes. The α-MoO:Te nanoflakes, which had been grown by vapor-phase epitaxy, clearly exhibited an A Raman band from symmetric stretching of υ(Mo-O-Mo) in the 2D-like ultrathin α-MoO:Te layer. Due to the intentional incorporation of smaller Te ions into bigger Mo sites, the pentacoordinated Mo bonds were created inside the orthorhombic α-MoO:Te lattice system. Since Mo ions have magnetic moments from unpaired electron spins, a large number of overlapped bound magnetic polarons could be formed ferromagnetic coupling with charged oxygen vacancies that are inevitably generated at pentacoordinated [MoO] centers. This gives rise to the increase in long-range ferromagnetic ordering and leads to room-temperature ferromagnetism in the entire α-MoO:Te solid-state system. The results may move a step closer to the demonstration of spin functionalities in the wide bandgap semiconductor α-MoO:Te.