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

S. E. Harrison, Liam James Collins-McIntyre, P. Schönherr, A. Vailionis, V. Srot, P. A. Van Aken, A. J. Kellock, A. Pushp, S. S P Parkin, J. S. Harris, B. Zhou, Y. L. Chen, T. Hesjedal*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

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.

Original languageEnglish
Article number15767
Number of pages7
JournalScientific Reports
Volume5
DOIs
Publication statusPublished - 27 Oct 2015

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