TY - JOUR
T1 - Site-Specific Contributions to the Band Inversion in a Topological Crystalline Insulator
AU - Koumoulis, Dimitrios
AU - Chasapis, Thomas Christos
AU - Leung, Belinda
AU - Taylor, Robert E.
AU - Stoumpos, Costas C.
AU - Calta, Nicholas P.
AU - Kanatzidis, Mercouri G.
AU - Bouchard, Louis Serge
N1 - Publisher Copyright:
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.
PY - 2015/8
Y1 - 2015/8
N2 - In a topological crystalline insulator (TCI) the inversion of the bulk valence and conduction bands is a necessary condition to observe surface metallic states. Solid solutions of Pb1-xSnxTe have been shown to be TCI, where band inversion occurs as a result of the band gap evolution upon alloying with Sn. The origins of this band inversion remain unclear. Herein the role of Sn insertion into the PbTe matrix is investigated for the p-type Pb1-xSnxTe series with x = 0, 0.35, 0.60, and 1.00 via nuclear magnetic resonance (NMR) and transport measurements. 207Pb, 119Sn, and 125Te line shapes, spin-lattice relaxation rates, and Knight shifts provide site-specific characterization of the electronic band structure. This probe of the electronic band structure shows that the band inversion is unaffected by lattice distortions but related to spatial electronic inhomogeneities formed by Sn incorporation into the PbTe matrix. Strong relativistic effects are found to be responsible for the band inversion, regardless of carrier type and concentration, suggesting a novel interpretation of the band gap evolution with composition. The temperature dependences of the NMR parameters reveal a negative temperature coefficient of the direct gap for SnTe and positive coefficient for PbTe.
AB - In a topological crystalline insulator (TCI) the inversion of the bulk valence and conduction bands is a necessary condition to observe surface metallic states. Solid solutions of Pb1-xSnxTe have been shown to be TCI, where band inversion occurs as a result of the band gap evolution upon alloying with Sn. The origins of this band inversion remain unclear. Herein the role of Sn insertion into the PbTe matrix is investigated for the p-type Pb1-xSnxTe series with x = 0, 0.35, 0.60, and 1.00 via nuclear magnetic resonance (NMR) and transport measurements. 207Pb, 119Sn, and 125Te line shapes, spin-lattice relaxation rates, and Knight shifts provide site-specific characterization of the electronic band structure. This probe of the electronic band structure shows that the band inversion is unaffected by lattice distortions but related to spatial electronic inhomogeneities formed by Sn incorporation into the PbTe matrix. Strong relativistic effects are found to be responsible for the band inversion, regardless of carrier type and concentration, suggesting a novel interpretation of the band gap evolution with composition. The temperature dependences of the NMR parameters reveal a negative temperature coefficient of the direct gap for SnTe and positive coefficient for PbTe.
KW - NMR properties
KW - band inversion
KW - electronic inhomogeneities
KW - lead tin telluride
KW - topological crystalline insulator
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U2 - 10.1002/aelm.201500117
DO - 10.1002/aelm.201500117
M3 - Article
AN - SCOPUS:84977097939
VL - 1
JO - Advanced Electronic Materials
JF - Advanced Electronic Materials
SN - 2199-160X
IS - 8
M1 - 1500117
ER -