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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.

No MeSH data available.


Resistivity as a function of pressure for Ag2Te at room temperature.
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f3: Resistivity as a function of pressure for Ag2Te at room temperature.

Mentions: In order to check on the change of topological nature and the assumption of a pressure-induced ETT in Ag2Te near 1.8 GPa, we performs high-pressure resistivity measurements which is believed as an effective supplementary mean for ADXRD measurements to identify electronic structural phase transition. Figure 3 shows the pressure dependence of resistivity for Ag2Te at room temperature. The electrical resistivity for Ag2Te at 1.8 GPa is nearly 3.3 times to that at ambient pressure, then the electrical resistivity presents a intense collapse and decreases relatively slowly beyond 2.0 GPa. Above ADXRD results have proved that there is no structural transformation until 2.2 GPa. This distinct change may come from ETT34. Therefore, in order to shed light on the notable change in the P21/c phase around 1.8 GPa, we carried out first-principles calculations, which is useful to investigate the effects of pressure-induced ETT on the electronic band structures and may discover the development of topological nature on Ag2Te. However, Zhao et al. performed first-principles calculation on P21/c and Cmca phase in order to study the pressure-induced metallization.


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)

Resistivity as a function of pressure for Ag2Te at room temperature.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Resistivity as a function of pressure for Ag2Te at room temperature.
Mentions: In order to check on the change of topological nature and the assumption of a pressure-induced ETT in Ag2Te near 1.8 GPa, we performs high-pressure resistivity measurements which is believed as an effective supplementary mean for ADXRD measurements to identify electronic structural phase transition. Figure 3 shows the pressure dependence of resistivity for Ag2Te at room temperature. The electrical resistivity for Ag2Te at 1.8 GPa is nearly 3.3 times to that at ambient pressure, then the electrical resistivity presents a intense collapse and decreases relatively slowly beyond 2.0 GPa. Above ADXRD results have proved that there is no structural transformation until 2.2 GPa. This distinct change may come from ETT34. Therefore, in order to shed light on the notable change in the P21/c phase around 1.8 GPa, we carried out first-principles calculations, which is useful to investigate the effects of pressure-induced ETT on the electronic band structures and may discover the development of topological nature on Ag2Te. However, Zhao et al. performed first-principles calculation on P21/c and Cmca phase in order to study the pressure-induced metallization.

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.