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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.

No MeSH data available.


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Transport properties of the best TlBiSe2 sample. (a) Field dependence of the Hall resistivity, . (b) Temperature dependence of the Seebeck coefficient. (c) Field dependence of the resistivity at 1.6 K. (d) Oscillatory component of magnetoresistance versus inverse of the magnetic fields. The solid line is a fit to data.
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Figure 7: Transport properties of the best TlBiSe2 sample. (a) Field dependence of the Hall resistivity, . (b) Temperature dependence of the Seebeck coefficient. (c) Field dependence of the resistivity at 1.6 K. (d) Oscillatory component of magnetoresistance versus inverse of the magnetic fields. The solid line is a fit to data.

Mentions: In this section, let me discuss the magneto transport of the best sample of TlBiSe2 (sample B in figure 6). Figure 7(a) shows the magnetic-field dependence of the Hall resistivity, , up to ±14 T. The solid line shows the linear fitting, and the lack of non-linearity (deviation from the linear fit is less than 1%) is indicative of the single-channel electronic transport. The carrier concentration of this sample is n = cm−3 [ = −145 ( cm3/C)], and this result is in agreement with low-field data in figure 6(b). Please note that the bulk conduction channel must govern the transport properties of the present sample, and thus the topological surface channel does not play an important role, unfortunately. Figure 7(c) shows the field dependence of the magnetoresistance up to 14 T. The data are symmetrized with respect to the magnetic field. At very low fields, no anomaly is observed, and thus weak antilocalization behavior is missing in this system. This result is indicative of the dominance of the bulk-channel transport. At high fields, magnetoresistance shows a clear oscillation. Since the oscillatory component of the magnetoresistance shows a periodicity of , this behavior is Shubnikov-de-Haas (SdH) oscillation. The frequency of the SdH oscillation is f = 296 T, and this gives = 9.48 × 106 cm−1 according to the Onsager relation, . The value is in good agreement with the ARPES result [21]. If a spherical Fermi surface (FS) is assumed, gives n = 2.88 cm−3. This value is smaller than n obtained from the Hall coefficient, but it can be understood if the FS is elongated along the -axis. Figure 3(b) shows the temperature dependence of the Seebeck coefficient, S. The negative sign of S is consistent with n-type doping in the present system.


Synthesis and characterization of 3D topological insulators: a case TlBi(S 1 − x Se x ) 2
Transport properties of the best TlBiSe2 sample. (a) Field dependence of the Hall resistivity, . (b) Temperature dependence of the Seebeck coefficient. (c) Field dependence of the resistivity at 1.6 K. (d) Oscillatory component of magnetoresistance versus inverse of the magnetic fields. The solid line is a fit to data.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: Transport properties of the best TlBiSe2 sample. (a) Field dependence of the Hall resistivity, . (b) Temperature dependence of the Seebeck coefficient. (c) Field dependence of the resistivity at 1.6 K. (d) Oscillatory component of magnetoresistance versus inverse of the magnetic fields. The solid line is a fit to data.
Mentions: In this section, let me discuss the magneto transport of the best sample of TlBiSe2 (sample B in figure 6). Figure 7(a) shows the magnetic-field dependence of the Hall resistivity, , up to ±14 T. The solid line shows the linear fitting, and the lack of non-linearity (deviation from the linear fit is less than 1%) is indicative of the single-channel electronic transport. The carrier concentration of this sample is n = cm−3 [ = −145 ( cm3/C)], and this result is in agreement with low-field data in figure 6(b). Please note that the bulk conduction channel must govern the transport properties of the present sample, and thus the topological surface channel does not play an important role, unfortunately. Figure 7(c) shows the field dependence of the magnetoresistance up to 14 T. The data are symmetrized with respect to the magnetic field. At very low fields, no anomaly is observed, and thus weak antilocalization behavior is missing in this system. This result is indicative of the dominance of the bulk-channel transport. At high fields, magnetoresistance shows a clear oscillation. Since the oscillatory component of the magnetoresistance shows a periodicity of , this behavior is Shubnikov-de-Haas (SdH) oscillation. The frequency of the SdH oscillation is f = 296 T, and this gives = 9.48 × 106 cm−1 according to the Onsager relation, . The value is in good agreement with the ARPES result [21]. If a spherical Fermi surface (FS) is assumed, gives n = 2.88 cm−3. This value is smaller than n obtained from the Hall coefficient, but it can be understood if the FS is elongated along the -axis. Figure 3(b) shows the temperature dependence of the Seebeck coefficient, S. The negative sign of S is consistent with n-type doping 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