| Autor: |
E. Bandiello, S. Gallego-Parra, A. Liang, J.A. Sans, V. Cuenca-Gotor, E. Lora da Silva, R. Vilaplana, P. Rodríguez-Hernández, A. Muñoz, D. Diaz-Anichtchenko, C. Popescu, F.G. Alabarse, C. Rudamas, C. Drasar, A. Segura, D. Errandonea, F.J. Manjón |
| Jazyk: |
angličtina |
| Rok vydání: |
2023 |
| Předmět: |
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| Zdroj: |
Materials Today Advances, Vol 19, Iss , Pp 100403- (2023) |
| Druh dokumentu: |
article |
| ISSN: |
2590-0498 |
| DOI: |
10.1016/j.mtadv.2023.100403 |
| Popis: |
GaGeTe is a layered topological semimetal that has been recently found to exist in at least two different polytypes, α-GaGeTe (R3¯m) and β-GaGeTe (P63mc). Here we report a joint experimental and theoretical study of the structural, vibrational, and electronic properties of these two polytypes in high-pressure conditions. Both polytypes show anisotropic compressibility and two phase transitions, above 7 and 15 GPa, respectively, as confirmed by XRD and Raman spectroscopy measurements. Although the nature of the high-pressure phases could not be confirmed, comparison with other chalcogenides and total-energy calculations allow us to propose possible high-pressure phases for both polytypes with an increase in coordination for Ga and Ge atoms from 4 to 6. In particular, the simplification of the X-ray pattern for both polytypes above 15 GPa suggests a transition to a structure of relatively higher symmetry than the original one. This result is consistent with the rocksalt-like high-pressure phases observed in parent III-VI semiconductors, such as GaTe, GaSe, and InSe. Pressure-induced amorphization is observed upon pressure release. The electronic band structures of α-GaGeTe and β-GaGeTe and their pressure dependence also show similarities to III-VI semiconductors, thus suggesting that the germanene-like sublayer induces a semimetallic character in both GaGeTe polytypes. Above 3 GPa, both polytypes lose their topological features, due to the opening of the direct band gap, while the reduction of the interlayer space increases the thermal conductivity at high pressure. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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