| Autor: |
Kutorasinski, K., Wiendlocha, B., Tobola, J., Kaprzyk, S. |
| Rok vydání: |
2014 |
| Předmět: |
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| Zdroj: |
Phys. Rev. B 89, 115205 (2014) |
| Druh dokumentu: |
Working Paper |
| DOI: |
10.1103/PhysRevB.89.115205 |
| Popis: |
We present a theoretical study of the influence of the relativistic effects on electronic band structure and thermopower of Mg2X(X= Si, Ge, Sn) semiconductors. The full potential Korringa-Kohn-Rostoker (KKR) method is used, and the detailed comparison between the fully relativistic and semi-relativistic electronic structure features is done. We show that the spin-orbit (S-O) interaction splits the valence band structure at Gamma point in good agreement with the experimental data, and this effect strongly depends on X atom. The S-O modifications of the topology of the Gamma-centered hole-like Fermi surface pockets lead to a change in electron transport properties, which are investigated using the Boltzmann approach. In addition, the simple and efficient method is presented for the calculation of density of states effective mass m*, and then used to examine the impact of relativistic effects on m*. It is found that S-O coupling of the valence bands reduces effective mass and therefore significantly lowers the thermopower, primarily in Mg2Sn, but also in Mg2Ge. A detrimental influence of the S-O interaction on thermoelectric performance of p-type Mg2X is analyzed in function of temperature (10-900 K) and carrier concentration (10^18-10^22 cm-3). Interestingly, similar calculations in n-type Mg2X, show negligible effect of the S-O interaction on lowest conduction bands and consequently also on the Seebeck coefficient. |
| Databáze: |
arXiv |
| Externí odkaz: |
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