An Efficient Dopant for Introducing Magnetism into Topological Insulator Bi 2 Se 3 .

In this work, we obtained an effective way to introduce magnetism into topological insulators, and successfully fabricated single crystal C-Bi 2 Se 3 . The structural, electrical and magnetic properties of non-magnetic element X (B, C and N) doped at Bi, Se1, Se2 and VDW gap sites of Bi 2 Se 3 were studied by the first principles. It is shown that the impurity bands formed inside the bulk inverted energy gap near the Fermi level with C doping Bi 2 Se 3 . Due to spin-polarized ferromagnetic coupling, the time inversion symmetry of Bi 2 Se 3 is destroyed. Remarkably, C is the most effective dopant because of the magnetic moment produced by doping at all positions. The experiment confirmed that the remnant ferromagnetism Mr is related to the C concentration. Theoretical calculations and experiments confirmed that carbon-doped Bi 2 Se 3 is ferromagnetic, which provides a plan for manipulating topological properties and exploring spintronic applications.