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

doi:10.1038/srep15767

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

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

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 language	English
Article number	15767
Number of pages	7
Journal	Scientific Reports
Volume	5
DOIs	https://doi.org/10.1038/srep15767
Publication status	Published - 27 Oct 2015

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title = "Massive Dirac fermion observed in lanthanide-doped topological insulator thin films",

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.",

author = "Harrison, \{S. E.\} and Collins-McIntyre, \{Liam James\} and P. Sch{\"o}nherr and A. Vailionis and V. Srot and \{Van Aken\}, \{P. A.\} and Kellock, \{A. J.\} and A. Pushp and Parkin, \{S. S P\} and Harris, \{J. S.\} and B. Zhou and Chen, \{Y. L.\} and T. Hesjedal",

note = "This publication arises from research funded by the John Fell Oxford University Press (OUP) Research Fund, a DARPA MESO Project (No. N66001-11-1-4105), and funding from the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative I3) and transnational access to MPI-IS (WP13). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF). S.E.H. was supported by the VPGE (Stanford University), L.C.M. by EPSRC (UK), and P.S. acknowledges partial funding from EPSRC, Corpus Christi College (Oxford), and the Studienstiftung des deutschen Volkes (Germany).",

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doi = "10.1038/srep15767",

language = "English",

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T1 - Massive Dirac fermion observed in lanthanide-doped topological insulator thin films

AU - Harrison, S. E.

AU - Collins-McIntyre, Liam James

AU - Schönherr, P.

AU - Vailionis, A.

AU - Srot, V.

AU - Van Aken, P. A.

AU - Kellock, A. J.

AU - Pushp, A.

AU - Parkin, S. S P

AU - Harris, J. S.

AU - Zhou, B.

AU - Chen, Y. L.

AU - Hesjedal, T.

N1 - This publication arises from research funded by the John Fell Oxford University Press (OUP) Research Fund, a DARPA MESO Project (No. N66001-11-1-4105), and funding from the European Union Seventh Framework Programme under Grant Agreement 312483 – ESTEEM2 (Integrated Infrastructure Initiative I3) and transnational access to MPI-IS (WP13). Part of this work was performed at the Stanford Nano Shared Facilities (SNSF). S.E.H. was supported by the VPGE (Stanford University), L.C.M. by EPSRC (UK), and P.S. acknowledges partial funding from EPSRC, Corpus Christi College (Oxford), and the Studienstiftung des deutschen Volkes (Germany).

PY - 2015/10/27

Y1 - 2015/10/27

N2 - 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.

AB - 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.

UR - https://www.scopus.com/pages/publications/84946064926

U2 - 10.1038/srep15767

DO - 10.1038/srep15767

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AN - SCOPUS:84946064926

SN - 2045-2322

VL - 5

JO - Scientific Reports

JF - Scientific Reports

M1 - 15767

ER -

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

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