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Electronic Topological Transition in Ag2Te at High-pressure.

Zhang Y, Li Y, Ma Y, Li Y, Li G, Shao X, Wang H, Cui T, Wang X, Zhu P - Sci Rep (2015)

Bottom Line: Here, a pressure-induced electronic topological transition (ETT) is firstly found in Ag2Te at 1.8 GPa.This result indicates that the best bulk insulating character and topological nature in Ag2Te can be obtained at this pressure.A pressure-induced metallization in Ag2Te is confirmed by the results of temperature-dependent resistivity measurements.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.

ABSTRACT
Recently, Ag2Te was experimentally confirmed to be a 3D topological insulator (TI) at ambient pressure. However, the high-pressure behaviors and properties of Ag2Te were rarely reported. Here, a pressure-induced electronic topological transition (ETT) is firstly found in Ag2Te at 1.8 GPa. Before ETT, the positive pressure coefficient of bulk band-gap, which is firstly found in TIs family, is found by both first-principle calculations and in situ high-pressure resistivity measurements. The electrical resistivity obtained at room temperature shows a maximum at 1.8 GPa, which is nearly 3.3 times to that at ambient pressure. This result indicates that the best bulk insulating character and topological nature in Ag2Te can be obtained at this pressure. Furthermore, the high-pressure structural behavior of Ag2Te has been investigated by in situ high-pressure synchrotron powder X-ray diffraction technique up to 33.0 GPa. The accurate pressure-induced phase transition sequence is firstly determined as P21/c → Cmca → Pnma. It is worth noting that the reported isostructural P21/c phase is not existed, and the reported structure of Cmca phase is corrected by CALYPSO methodology. The second high-pressure structure, a long puzzle to previous reports, is determined as Pnma phase. A pressure-induced metallization in Ag2Te is confirmed by the results of temperature-dependent resistivity measurements.

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(a) Temperature dependence of resistivity for Ag2Te. The inset shows resistivity vs temperature at 1.6, 1.8, and 4.1 GPa, respectively. (b) Pressure dependence of the carrier activation energy for Ag2Te.
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f5: (a) Temperature dependence of resistivity for Ag2Te. The inset shows resistivity vs temperature at 1.6, 1.8, and 4.1 GPa, respectively. (b) Pressure dependence of the carrier activation energy for Ag2Te.

Mentions: Moreover, the resistivity as a function of temperature at various fixed pressures was shown in Fig. 5(a). Before ETT, it is noticed that the resistivity decreases with increasing temperature, demonstrating specific semiconductor behaviors. From Fig. 5(a), the bulk insulating character of Ag2Te becomes better and better with increasing pressure, which is a good agreement with our electronic band structure results. As shown in the inset of Fig. 5(a), the resistivity displays a positive relationship with increasing temperature at 4.1 GPa, which implies that the Cmca phase performs a metallic behavior. Therefore, the pressure-induced insulator-metal transition was experimentally confirmed by the temperature-dependent resistivity results. The carrier activation energy could be obtained by linearly fitting the plots of lnρ versus 1000/T38. As shown in Fig. 5(b), there is a continued increase in the carrier activation energy with increasing pressure, indicating a development of carriers energy barriers, which induces that the transport of 3D carrier becomes harder and harder by applying pressure. Therefore, at 1.8 GPa, the best bulk insulating character is obtained, which is the best topological nature of Ag2Te by applying pressure.


Electronic Topological Transition in Ag2Te at High-pressure.

Zhang Y, Li Y, Ma Y, Li Y, Li G, Shao X, Wang H, Cui T, Wang X, Zhu P - Sci Rep (2015)

(a) Temperature dependence of resistivity for Ag2Te. The inset shows resistivity vs temperature at 1.6, 1.8, and 4.1 GPa, respectively. (b) Pressure dependence of the carrier activation energy for Ag2Te.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4588579&req=5

f5: (a) Temperature dependence of resistivity for Ag2Te. The inset shows resistivity vs temperature at 1.6, 1.8, and 4.1 GPa, respectively. (b) Pressure dependence of the carrier activation energy for Ag2Te.
Mentions: Moreover, the resistivity as a function of temperature at various fixed pressures was shown in Fig. 5(a). Before ETT, it is noticed that the resistivity decreases with increasing temperature, demonstrating specific semiconductor behaviors. From Fig. 5(a), the bulk insulating character of Ag2Te becomes better and better with increasing pressure, which is a good agreement with our electronic band structure results. As shown in the inset of Fig. 5(a), the resistivity displays a positive relationship with increasing temperature at 4.1 GPa, which implies that the Cmca phase performs a metallic behavior. Therefore, the pressure-induced insulator-metal transition was experimentally confirmed by the temperature-dependent resistivity results. The carrier activation energy could be obtained by linearly fitting the plots of lnρ versus 1000/T38. As shown in Fig. 5(b), there is a continued increase in the carrier activation energy with increasing pressure, indicating a development of carriers energy barriers, which induces that the transport of 3D carrier becomes harder and harder by applying pressure. Therefore, at 1.8 GPa, the best bulk insulating character is obtained, which is the best topological nature of Ag2Te by applying pressure.

Bottom Line: Here, a pressure-induced electronic topological transition (ETT) is firstly found in Ag2Te at 1.8 GPa.This result indicates that the best bulk insulating character and topological nature in Ag2Te can be obtained at this pressure.A pressure-induced metallization in Ag2Te is confirmed by the results of temperature-dependent resistivity measurements.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China.

ABSTRACT
Recently, Ag2Te was experimentally confirmed to be a 3D topological insulator (TI) at ambient pressure. However, the high-pressure behaviors and properties of Ag2Te were rarely reported. Here, a pressure-induced electronic topological transition (ETT) is firstly found in Ag2Te at 1.8 GPa. Before ETT, the positive pressure coefficient of bulk band-gap, which is firstly found in TIs family, is found by both first-principle calculations and in situ high-pressure resistivity measurements. The electrical resistivity obtained at room temperature shows a maximum at 1.8 GPa, which is nearly 3.3 times to that at ambient pressure. This result indicates that the best bulk insulating character and topological nature in Ag2Te can be obtained at this pressure. Furthermore, the high-pressure structural behavior of Ag2Te has been investigated by in situ high-pressure synchrotron powder X-ray diffraction technique up to 33.0 GPa. The accurate pressure-induced phase transition sequence is firstly determined as P21/c → Cmca → Pnma. It is worth noting that the reported isostructural P21/c phase is not existed, and the reported structure of Cmca phase is corrected by CALYPSO methodology. The second high-pressure structure, a long puzzle to previous reports, is determined as Pnma phase. A pressure-induced metallization in Ag2Te is confirmed by the results of temperature-dependent resistivity measurements.

No MeSH data available.


Related in: MedlinePlus