Ultrafast relaxation of symmetry-breaking photo-induced atomic forces
| Autor: | O'Mahony, Shane M., Murphy-Armando, Felipe, Murray, Éamonn D., Querales-Flores, José D., Savić, Ivana, Fahy, Stephen |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 123, 087401 (2019) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.123.087401 |
| Popis: | We present a first-principles method for the calculation of the temperature-dependent relaxation of symmetry-breaking atomic driving forces in photoexcited systems. We calculate the phonon-assisted decay of the photoexcited force on the low-symmetry $E_g$ mode following absorption of an ultrafast pulse in the prototypical group-V semimetals, Bi, Sb and As. The force decay lifetimes for Bi and Sb are of the order of $10$ fs and in good agreement with recent experiments, demonstrating that electron-phonon scattering is the dominant mechanism relaxing the symmetry-breaking forces. Calculations for a range of absorbed photon energies suggest that larger amplitude, symmetry-breaking atomic motion may be induced by choosing a pump photon energy which maximises the product of the initial $E_g$ force and its lifetime. We also find that the high-symmetry $A_{1g}$ force undergoes a partial decay to a non-zero constant on similar timescales, which has not yet been measured in experiments. We observe that the imaginary part of the electron self-energy, averaged over the photoexcited carrier distribution, provides a reasonable estimate for the decay rate of symmetry-breaking forces. Comment: 7 pages, 9 figures |
| Databáze: | arXiv |
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