##### Description

__Oliver Rader__

^{1}1, Helmholtz-Zentrum Berlin, Berlin, , Germany

Magnetic topological insulators enable the quantum anomalous Hall effect with edge states for lossless charge transport. These edge states are hosted by a magnetic band gap at the Dirac point which, however, never been observed directly by angle-resolved photoelectron spectroscopy (ARPES) despite its importance for the achievable operation temperature of devices. Here, ARPES is employed to demonstrate a magnetic gap at the Dirac point of Mn-doped Bi_{2}Te_{3} films [1]. The gap is 32 meV wide [1] and thus twice as large as predicted by density functional theory [2]. We discuss reasons for this discrepancy. Moreover, the control system Mn-doped Bi_{2}Se_{3 }does not show a magnetic gap [3].

[1] P. S. Mandal, S. Wimmer, E. D. L. Rienks, O. Caha, V. V. Volobuiev, G. Springholz, G. Bauer, A. Ney, S. Khan, J. Minár, J. Sánchez-Barriga, A. Varykhalov, O. Rader et al. (unpublished)

[2] J. Henk, M. Flieger, I. V. Maznichenko, I. Mertig, A. Ernst, S. V. Eremeev, and E. V. Chulkov, Phys. Rev. Lett. 109, 076801 (2012)

[3] J. Sánchez-Barriga, A. Varykhalov, G. Springholz, H. Steiner, R. Kirchschlager, G. Bauer, O. Caha, E. Schierle, E. Weschke, A. A. Ünal, S. Valencia, M. Dunst, J. Braun, H. Ebert, J. Minár, E. Golias, L.V. Yashina, A. Ney, V. Holý, O. Rader, Nat. Commun. 7, 10559 (2016)