A two-step doping process, magnetic followed by charge or vice versa, is required to produce massive topological surface states (TSS) in topological insulators for many physics and device applications. Here, we demonstrate simultaneous magnetic and hole doping achieved with a single dopant, carbon, in ${\mathrm{Bi}}_2{\mathrm{Se}}_3$ by first-principles calculations. Carbon substitution for Se (${\mathrm{C}}_{\mathrm{Se}}$) results in an opening of a sizable surface Dirac gap (up to 82 meV), while the Fermi level remains inside the bulk gap and close to the Dirac point at moderate doping concentrations. The strong localization of $2p$ states of ${\mathrm{C}}_{\mathrm{Se}}$ favors spontaneous spin polarization via a $p\mathrm{\text{−}}p$ interaction and formation of ordered magnetic moments mediated by surface states. Meanwhile, holes are introduced into the system by ${\mathrm{C}}_{\mathrm{Se}}$. This dual function of carbon doping suggests a simple way to realize insulating massive TSS.

• Received 20 March 2013

DOI:https://doi.org/10.1103/PhysRevLett.111.236803