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Carrier-mediated magnetism in transition metal doped Bi₂Se₃ topological insulator
Tome M Schmidt1, R H Miwa, A Fazzio
1Instituto de Física, Universidade Federal de Uberlândia, Caixa Postal 593, CEP 38400-902, Uberlândia, Minas Gerais, Brazil.
Abstract:
The Dirac surface states of topological insulators are protected by time-reversal symmetry, suppressing backscattering. Magnetic impurities adsorbed on the surface of topological insulators are expected to degrade the coherence of these protected surface states, breaking time-reversal symmetry. Some results are in agreement with this prediction. There are others where no bandgap opening was observed. Here, based upon first principles calculations, we show that one mechanism that plays a key role in these controversial results is the intrinsic carrier concentration. The magnetic phase of Fe-, Co- and Ni-doped Bi2Se3 has been computed and compared to the same systems in the presence of n- or p-type doping. Our results show that the magnetic phase is dependent on both the carrier concentration and the magnetic impurity coverage, resulting in a phase diagram for the existence or not of the protected Dirac states.
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