Topological States Ruled by Stacking Faults in Bi2Se3 and Bi2Te3
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Transcript of Topological States Ruled by Stacking Faults in Bi2Se3 and Bi2Te3
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Topological States Ruled by Stacking Faults inBi2Se3 and Bi2Te3
Leandro Seixas, L. B. Abdalla, T. M. Schmidt, A. Fazzio and R. H. Miwa
Universidade de São PauloSão Paulo, SP, Brazil
Rensselaer Polytechnic InstituteTroy, NY, USA
Financial support
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Topological Insulators: Bi2Se3 and Bi2Te3
120° z-axisrotation of A
240° z-axisrotation of A
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Stacking Faults inBi2Se3 and Bi2Te3
IntrinsicStacking Fault
ExtrinsicStacking Fault
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Methods• First principles calculations based upon
Density Functional Theory (DFT)
• LDA functional for structural propertiesbecause weak interactions among QLs
• GGA-PBE functional for electronic propertieselectronic band structure
• PAW method
• Spin-Orbit couplingonly for electronic properties
• VASP code
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QL-QL interactionthe binding energy of two QL, in function of z-separation
three non-equivalent stacks between QLs
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Stacking Faults Energies
γISF (mJ/m2) γESF (mJ/m2)
Bi2Se3 212 107
Bi2Te3 196 82
Si[1] 33 26
Ni[2] 187 178
Th[2] 320 291
[1] M. Y. Chou, M. L. Cohen, S. G. Louie, Phys Rev. B32, 7979 (1985).[2] N. M. Rosengaard, H. L. Skriver, Phys. Rev. B47 12865 (1993).
What is the energy required to form these defects?
from our calculations
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Band Structure(Bi2Se3 Bulk)
c1
v1 v2
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Band Structure(Bi2Te3 Bulk)
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Band Structure(Bi2Te3 Bulk)
Topological metallic states
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Band Structure(QL-QL distance)
where these “topological states” come from?
without stacking faults, but with larger z-separation between QLs
2.50 3.15 4.15 7.15
2.91 3.26 3.76 7.56
Δzeq = 2.15
Δzeq = 2.56
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Band Structure(Surface)
Dirac point shift
stacking faults near the surface (about 10 Å)
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Band Structure(Surface)
Dirac point shift
stacking faults near the surface (about 10 Å)
Surface states near stacking fault
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Band Structure(Surface)
Dirac point shift
stacking faults near the surface (about 10 Å)
Pristine surface
Surface states near stacking fault
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Conclusions
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Conclusions
Stacking faults in Bi2Te3 leads topological states in bulk.
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Conclusions
Stacking faults in Bi2Te3 leads topological states in bulk.
These topological states come from the larger z-separation between QL.
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Conclusions
Stacking faults in Bi2Te3 leads topological states in bulk.
These topological states come from the larger z-separation between QL.
Interaction between surface and stacking fault shifts the Dirac point.
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Conclusions
Acknowledgement:CNPq/INCT, CAPES, CENAPAD/SP, FAPEMIG and FAPESP
Stacking faults in Bi2Te3 leads topological states in bulk.
These topological states come from the larger z-separation between QL.
Interaction between surface and stacking fault shifts the Dirac point.
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