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Synthesis and characterization of 3D topological insulators: a case TlBi(S 1 − x Se x ) 2

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ABSTRACT

In this article, practical methods for synthesizing Tl-based ternary III-V-VI2 chalcogenide TlBi(SSex)2 are described in detail, along with characterization by x-ray diffraction and charge transport properties. The TlBi(SSex)2 system is interesting because it shows a topological phase transition, where a topologically nontrivial phase changes to a trivial phase without changing the crystal structure qualitatively. In addition, Dirac semimetals whose bulk band structure shows a Dirac-like dispersion are considered to exist near the topological phase transition. The technique shown here is also generally applicable for other chalcogenide topological insulators, and will be useful for studying topological insulators and related materials.

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Temperature dependences of the resistivity for TlBi(SSex)2, x = 1.0, 0.6, 0.4, and 0.1, up to 500 K.
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Figure 8: Temperature dependences of the resistivity for TlBi(SSex)2, x = 1.0, 0.6, 0.4, and 0.1, up to 500 K.

Mentions: From the transport properties at high temperatures, one may extract the energy gap if an activation behavior is observed [3]. In the present experiment I could not observe any activation behavior either in the resistivity or the Hall coefficient. However, the temperature dependence of resistivity shows some difference between Se-rich and Se-poor samples (figure 8). The resistivity above 300 K and the temperature dependences in x = 0.1 and 0.4 samples show a significant increase up to 500 K, whereas the increase is modest in x = 0.6 and 1.0 samples. In all these samples, the charge carriers are electrons, and thus the chemical potential is located in the conduction band. The observed behavior suggests that the responsible bands for the Se-rich composition and the other are different from each other, and thus it is suggested that band inversion occurs when x changes from 0.4 to 0.6 in the present system.


Synthesis and characterization of 3D topological insulators: a case TlBi(S 1 − x Se x ) 2
Temperature dependences of the resistivity for TlBi(SSex)2, x = 1.0, 0.6, 0.4, and 0.1, up to 500 K.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036500&req=5

Figure 8: Temperature dependences of the resistivity for TlBi(SSex)2, x = 1.0, 0.6, 0.4, and 0.1, up to 500 K.
Mentions: From the transport properties at high temperatures, one may extract the energy gap if an activation behavior is observed [3]. In the present experiment I could not observe any activation behavior either in the resistivity or the Hall coefficient. However, the temperature dependence of resistivity shows some difference between Se-rich and Se-poor samples (figure 8). The resistivity above 300 K and the temperature dependences in x = 0.1 and 0.4 samples show a significant increase up to 500 K, whereas the increase is modest in x = 0.6 and 1.0 samples. In all these samples, the charge carriers are electrons, and thus the chemical potential is located in the conduction band. The observed behavior suggests that the responsible bands for the Se-rich composition and the other are different from each other, and thus it is suggested that band inversion occurs when x changes from 0.4 to 0.6 in the present system.

View Article: PubMed Central - PubMed

ABSTRACT

In this article, practical methods for synthesizing Tl-based ternary III-V-VI2 chalcogenide TlBi(SSex)2 are described in detail, along with characterization by x-ray diffraction and charge transport properties. The TlBi(SSex)2 system is interesting because it shows a topological phase transition, where a topologically nontrivial phase changes to a trivial phase without changing the crystal structure qualitatively. In addition, Dirac semimetals whose bulk band structure shows a Dirac-like dispersion are considered to exist near the topological phase transition. The technique shown here is also generally applicable for other chalcogenide topological insulators, and will be useful for studying topological insulators and related materials.

No MeSH data available.


Related in: MedlinePlus