Publication details

Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi1-xMnx)(2)Se-3

Authors	SANCHEZ-BARRIGA J. VARYKHALOV A. SPRINGHOLZ G. STEINER H. KIRCHSCHLAGER R. BAUER G. CAHA Ondřej SCHIERLE E. WESCHKE E. UENAL A. A. VALENCIA S. DUNST M. BRAUN J. EBERT H. MINAR J. GOLIAS E. YASHINA L. V. NEY A. HOLÝ Václav RADER O.
Year of publication	2016
Type	Article in Periodical
Magazine / Source	Nature Communications
MU Faculty or unit	Central European Institute of Technology
Citation
web	http://www.nature.com/articles/ncomms10559
Doi	http://dx.doi.org/10.1038/ncomms10559
Field	Solid matter physics and magnetism
Keywords	SURFACE; FERROMAGNETISM; TRANSITION; GA1-XMNXAS; FERMIONS
Description	Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi1-xMnx)(2)Se-3 is a prototypical magnetic topological insulator with a pronounced surface band gap of similar to 100 meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection.