Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

Duming Zhang, Anthony Raymond Richardella, David W. Rench, Su Yang Xu, Abhinav Kandala, Thomas C. Flanagan, Haim Beidenkopf, Andrew L. Yeats, Bob B. Buckley, Paul V. Klimov, David D. Awschalom, Ali Yazdani, Peter Schiffer, M. Zahid Hasan, Nitin Samarth

Research output: Contribution to journalArticle

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Abstract

The breaking of time-reversal symmetry by ferromagnetism is predicted to yield profound changes to the electronic surface states of a topological insulator. Here, we report on a concerted set of structural, magnetic, electrical, and spectroscopic measurements of Mn-Bi2Se3 thin films wherein photoemission and x-ray magnetic circular dichroism studies have recently shown surface ferromagnetism in the temperature range 15K≤T≤100 K, accompanied by a suppressed density of surface states at the Dirac point. Secondary-ion mass spectroscopy and scanning tunneling microscopy reveal an inhomogeneous distribution of Mn atoms, with a tendency to segregate towards the sample surface. Magnetometry and anisotropic magnetoresistance measurements are insensitive to the high-temperature ferromagnetism seen in surface studies, revealing instead a low-temperature ferromagnetic phase at T ≲5 K. The absence of both a magneto-optical Kerr effect and an anomalous Hall effect suggests that this low-temperature ferromagnetism is unlikely to be a homogeneous bulk phase but likely originates in nanoscale near-surface regions of the bulk where magnetic atoms segregate during sample growth. Although the samples are not ideal, with both bulk and surface contributions to electron transport, we measure a magnetoconductance whose behavior is qualitatively consistent with predictions that the opening of a gap in the Dirac spectrum drives quantum corrections to the conductance in topological insulators from the symplectic to the orthogonal class.

Original languageEnglish (US)
Article number205127
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number20
DOIs
StatePublished - Nov 26 2012

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Ferromagnetism
Surface states
ferromagnetism
insulators
Enhanced magnetoresistance
Optical Kerr effect
magnetic measurement
Atoms
Temperature
Hall effect
Dichroism
Photoemission
Scanning tunneling microscopy
Kerr effects
Spectroscopy
Ions
electrical measurement
dichroism
X rays
Thin films

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Zhang, Duming ; Richardella, Anthony Raymond ; Rench, David W. ; Xu, Su Yang ; Kandala, Abhinav ; Flanagan, Thomas C. ; Beidenkopf, Haim ; Yeats, Andrew L. ; Buckley, Bob B. ; Klimov, Paul V. ; Awschalom, David D. ; Yazdani, Ali ; Schiffer, Peter ; Hasan, M. Zahid ; Samarth, Nitin. / Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator. In: Physical Review B - Condensed Matter and Materials Physics. 2012 ; Vol. 86, No. 20.
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abstract = "The breaking of time-reversal symmetry by ferromagnetism is predicted to yield profound changes to the electronic surface states of a topological insulator. Here, we report on a concerted set of structural, magnetic, electrical, and spectroscopic measurements of Mn-Bi2Se3 thin films wherein photoemission and x-ray magnetic circular dichroism studies have recently shown surface ferromagnetism in the temperature range 15K≤T≤100 K, accompanied by a suppressed density of surface states at the Dirac point. Secondary-ion mass spectroscopy and scanning tunneling microscopy reveal an inhomogeneous distribution of Mn atoms, with a tendency to segregate towards the sample surface. Magnetometry and anisotropic magnetoresistance measurements are insensitive to the high-temperature ferromagnetism seen in surface studies, revealing instead a low-temperature ferromagnetic phase at T ≲5 K. The absence of both a magneto-optical Kerr effect and an anomalous Hall effect suggests that this low-temperature ferromagnetism is unlikely to be a homogeneous bulk phase but likely originates in nanoscale near-surface regions of the bulk where magnetic atoms segregate during sample growth. Although the samples are not ideal, with both bulk and surface contributions to electron transport, we measure a magnetoconductance whose behavior is qualitatively consistent with predictions that the opening of a gap in the Dirac spectrum drives quantum corrections to the conductance in topological insulators from the symplectic to the orthogonal class.",
author = "Duming Zhang and Richardella, {Anthony Raymond} and Rench, {David W.} and Xu, {Su Yang} and Abhinav Kandala and Flanagan, {Thomas C.} and Haim Beidenkopf and Yeats, {Andrew L.} and Buckley, {Bob B.} and Klimov, {Paul V.} and Awschalom, {David D.} and Ali Yazdani and Peter Schiffer and Hasan, {M. Zahid} and Nitin Samarth",
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Zhang, D, Richardella, AR, Rench, DW, Xu, SY, Kandala, A, Flanagan, TC, Beidenkopf, H, Yeats, AL, Buckley, BB, Klimov, PV, Awschalom, DD, Yazdani, A, Schiffer, P, Hasan, MZ & Samarth, N 2012, 'Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator', Physical Review B - Condensed Matter and Materials Physics, vol. 86, no. 20, 205127. https://doi.org/10.1103/PhysRevB.86.205127

Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator. / Zhang, Duming; Richardella, Anthony Raymond; Rench, David W.; Xu, Su Yang; Kandala, Abhinav; Flanagan, Thomas C.; Beidenkopf, Haim; Yeats, Andrew L.; Buckley, Bob B.; Klimov, Paul V.; Awschalom, David D.; Yazdani, Ali; Schiffer, Peter; Hasan, M. Zahid; Samarth, Nitin.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 86, No. 20, 205127, 26.11.2012.

Research output: Contribution to journalArticle

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T1 - Interplay between ferromagnetism, surface states, and quantum corrections in a magnetically doped topological insulator

AU - Zhang, Duming

AU - Richardella, Anthony Raymond

AU - Rench, David W.

AU - Xu, Su Yang

AU - Kandala, Abhinav

AU - Flanagan, Thomas C.

AU - Beidenkopf, Haim

AU - Yeats, Andrew L.

AU - Buckley, Bob B.

AU - Klimov, Paul V.

AU - Awschalom, David D.

AU - Yazdani, Ali

AU - Schiffer, Peter

AU - Hasan, M. Zahid

AU - Samarth, Nitin

PY - 2012/11/26

Y1 - 2012/11/26

N2 - The breaking of time-reversal symmetry by ferromagnetism is predicted to yield profound changes to the electronic surface states of a topological insulator. Here, we report on a concerted set of structural, magnetic, electrical, and spectroscopic measurements of Mn-Bi2Se3 thin films wherein photoemission and x-ray magnetic circular dichroism studies have recently shown surface ferromagnetism in the temperature range 15K≤T≤100 K, accompanied by a suppressed density of surface states at the Dirac point. Secondary-ion mass spectroscopy and scanning tunneling microscopy reveal an inhomogeneous distribution of Mn atoms, with a tendency to segregate towards the sample surface. Magnetometry and anisotropic magnetoresistance measurements are insensitive to the high-temperature ferromagnetism seen in surface studies, revealing instead a low-temperature ferromagnetic phase at T ≲5 K. The absence of both a magneto-optical Kerr effect and an anomalous Hall effect suggests that this low-temperature ferromagnetism is unlikely to be a homogeneous bulk phase but likely originates in nanoscale near-surface regions of the bulk where magnetic atoms segregate during sample growth. Although the samples are not ideal, with both bulk and surface contributions to electron transport, we measure a magnetoconductance whose behavior is qualitatively consistent with predictions that the opening of a gap in the Dirac spectrum drives quantum corrections to the conductance in topological insulators from the symplectic to the orthogonal class.

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