Topological phases in two-dimensional transition metal halides and oxides

The structural, electronic and magnetic properties of 2D transition metal halides (HfX, X=F, Cl, Br) and transition metal oxides (V 2 O 3 ) are investigated using first-principles simulations, based on density functional theory. The 2D hafnium halides are predicted to be topological insulators, with bulk energy band gaps in the range of 0.12-0.3S eV. On the other hand, 2D V 2 O 3 is predicted to be a Dirac half-metal, hosting the anomalous quantum Hall state, due to the coexistence of topological and ferromagnetic phases. These 2D materials are potentially interesting for novel electronic and spintronic devices, due to the (dissipationless) transport of carriers along spin-polarized edge states.