Massive Dirac fermion observed in lanthanide-doped topological insulator thin films

Journal article

The breaking of time reversal symmetry (TRS) in three-dimensional (3D) topological insulators (TIs) and thus the opening of a ‘Dirac-mass gap’ in the linearly dispersed Dirac surface state, is a prerequisite for unlocking exotic physical states. Introducing ferromagnetic long-range order by transition metal doping has been shown to break TRS. Here, we present the study of lanthanide (Ln) doped Bi2Te3, where the magnetic doping with high-moment lanthanides promises large energy gaps. Using molecular beam epitaxy, single-crystalline, rhombohedral thin films with Ln concentrations of up to ~35%, substituting on Bi sites, were achieved for Dy, Gd and Ho doping. Angle-resolved photoemission spectroscopy shows the characteristic Dirac cone for Gd and Ho doping. In contrast, for Dy doping above a critical doping concentration, a gap opening is observed via the decreased spectral intensity at the Dirac point, indicating a topological quantum phase transition persisting up to room-temperature.

Authors: Harrison, SE; Collins-McIntyre, LJ; Schönherr, P; Vailionis, A; Srot, V

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Publishing Group
• Journal: Scientific Reports
• Volume: 5
• Issue: 1
• Article number: 15767
• Publication date: 2015-10-27
• Acceptance date: 2015-09-30
• DOI: 10.1038/srep15767
• ISSN: 2045-2322
• Language: English