Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
Topological surface states in thick partially relaxed HgTe films. / Savchenko, M. L.; Kozlov, D. A.; Vasilev, N. N. и др.
в: Physical Review B, Том 99, № 19, 195423, 14.05.2019.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Topological surface states in thick partially relaxed HgTe films
AU - Savchenko, M. L.
AU - Kozlov, D. A.
AU - Vasilev, N. N.
AU - Kvon, Z. D.
AU - Mikhailov, N. N.
AU - Dvoretsky, S. A.
AU - Kolesnikov, A. V.
N1 - Publisher Copyright: © 2019 American Physical Society.
PY - 2019/5/14
Y1 - 2019/5/14
N2 - Surface states of topological insulators (TIs) have been playing the central role in the majority of outstanding investigations in low-dimensional electron systems for more than 10 years. TIs based on high-quality strained HgTe films demonstrate a variety of subtle physical effects. The strain leads to a bulk band gap but limits a maximum HgTe strained film thickness, and therefore, the majority of experiments were performed on films with a thickness of less than 100 nm. Since a spatial separation of topological states is crucial for the study of a single-surface response, it is essential to increase the HgTe thickness further. In this work, by combining transport measurements together with capacitance spectroscopy, we perform an analysis of a 200-nm partially relaxed HgTe film. The Drude fit of the classical magnetotransport reveals the ambipolar electron-hole transport with a high electron mobility. A detailed analysis of Shubnikov-de Haas oscillations in both conductivity and capacitance allows us to distinguish three groups of electrons, identified as electrons on top and bottom surfaces and bulk electrons. The indirect bulk energy gap value is found to be close to zero. It is established that the significant gap decrease does not affect the surface states, which are found to be well resolved and spin nondegenerate. The presented techniques allow investigations of other three-dimensional TIs, regardless of the presence of bulk conductivity.
AB - Surface states of topological insulators (TIs) have been playing the central role in the majority of outstanding investigations in low-dimensional electron systems for more than 10 years. TIs based on high-quality strained HgTe films demonstrate a variety of subtle physical effects. The strain leads to a bulk band gap but limits a maximum HgTe strained film thickness, and therefore, the majority of experiments were performed on films with a thickness of less than 100 nm. Since a spatial separation of topological states is crucial for the study of a single-surface response, it is essential to increase the HgTe thickness further. In this work, by combining transport measurements together with capacitance spectroscopy, we perform an analysis of a 200-nm partially relaxed HgTe film. The Drude fit of the classical magnetotransport reveals the ambipolar electron-hole transport with a high electron mobility. A detailed analysis of Shubnikov-de Haas oscillations in both conductivity and capacitance allows us to distinguish three groups of electrons, identified as electrons on top and bottom surfaces and bulk electrons. The indirect bulk energy gap value is found to be close to zero. It is established that the significant gap decrease does not affect the surface states, which are found to be well resolved and spin nondegenerate. The presented techniques allow investigations of other three-dimensional TIs, regardless of the presence of bulk conductivity.
UR - http://www.scopus.com/inward/record.url?scp=85066408787&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.99.195423
DO - 10.1103/PhysRevB.99.195423
M3 - Article
AN - SCOPUS:85066408787
VL - 99
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 19
M1 - 195423
ER -
ID: 20344051