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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.


(a) Lattice parameters and (b) lattice constant ratios as a function of pressure for the P21/c phase. The solid lines are guide for the eyes. Errors given by the GSAS EXPGUI package are smaller than the marker sizes.
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f2: (a) Lattice parameters and (b) lattice constant ratios as a function of pressure for the P21/c phase. The solid lines are guide for the eyes. Errors given by the GSAS EXPGUI package are smaller than the marker sizes.

Mentions: As shown in Fig. 2(a), all the lattice parameters including angle β in the P21/c phase monotonically decrease with increasing pressure. The linear compressibility of the different axes in the P21/c phase are κa = 0.0664(3) GPa−1, κb = 0.0230(7) GPa−1, and κc = 0.0314(3) GPa−1, respectively. It can be seen that the b and c axes are less compressible, which is due to Ag1 atoms are all located in bc plane, as shown in Supplementary Fig. S8(b), bringing in stronger Ag1-Ag1 interaction. As shown in Fig. 2(b), all the lattice constant ratios display notable changes in compressibility near 1.8 GPa. By taking into account that the ETTs, a modification of the topology of the Fermi surface, are verified by the changes in compressibility of the lattice constant ratios in other TIs—Bi2Te3, Bi2Se3 and Sb2Te325, the above abnormal changes may be ascribed to an ETT around 1.8 GPa.


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) Lattice parameters and (b) lattice constant ratios as a function of pressure for the P21/c phase. The solid lines are guide for the eyes. Errors given by the GSAS EXPGUI package are smaller than the marker sizes.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: (a) Lattice parameters and (b) lattice constant ratios as a function of pressure for the P21/c phase. The solid lines are guide for the eyes. Errors given by the GSAS EXPGUI package are smaller than the marker sizes.
Mentions: As shown in Fig. 2(a), all the lattice parameters including angle β in the P21/c phase monotonically decrease with increasing pressure. The linear compressibility of the different axes in the P21/c phase are κa = 0.0664(3) GPa−1, κb = 0.0230(7) GPa−1, and κc = 0.0314(3) GPa−1, respectively. It can be seen that the b and c axes are less compressible, which is due to Ag1 atoms are all located in bc plane, as shown in Supplementary Fig. S8(b), bringing in stronger Ag1-Ag1 interaction. As shown in Fig. 2(b), all the lattice constant ratios display notable changes in compressibility near 1.8 GPa. By taking into account that the ETTs, a modification of the topology of the Fermi surface, are verified by the changes in compressibility of the lattice constant ratios in other TIs—Bi2Te3, Bi2Se3 and Sb2Te325, the above abnormal changes may be ascribed to an ETT around 1.8 GPa.

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.