Electronic band structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Sb</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Te</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>
Ivan Mohelský, J. Wyzula, F. Le Mardelé, Farzin Abadizaman, Ondřej Caha, A. Dubroka, Xiaodong Sun, Chang-Woo Cho, B. A. Piot, M. F. Tanzim, Irene Aguilera, G. Bauer, G. Springholz, M. Orlita
Abstract
We report on Landau-level spectroscopy of an epitaxially grown thin film of the topological insulator <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msub><a:mi>Sb</a:mi><a:mn>2</a:mn></a:msub><a:msub><a:mi>Te</a:mi><a:mn>3</a:mn></a:msub></a:mrow></a:math>, complemented by ellipsometry and magnetotransport measurements. The observed response suggests that <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:msub><b:mi>Sb</b:mi><b:mn>2</b:mn></b:msub><b:msub><b:mi>Te</b:mi><b:mn>3</b:mn></b:msub></b:mrow></b:math> is a direct-gap semiconductor with the fundamental band gap located at the <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mi mathvariant="normal">Γ</c:mi></c:math> point or along the trigonal axis, and its width reaches <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:msub><e:mi>E</e:mi><e:mi>g</e:mi></e:msub><e:mo>=</e:mo><e:mrow><e:mo>(</e:mo><e:mn>190</e:mn><e:mo>±</e:mo><e:mn>10</e:mn><e:mo>)</e:mo></e:mrow></e:mrow></e:math> meV at low temperatures. Our data also indicate the presence of other low-energy extrema with a higher multiplicity in both the conduction and valence bands. The conclusions based on our experimental data are confronted with and to a great extent corroborated by the electronic band structure calculated using the <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:mrow><f:mi>G</f:mi><f:mi>W</f:mi></f:mrow></f:math> method. Published by the American Physical Society 2024