Extreme phonon softening in laser-excited Bismuth - towards an inverse Peierls-transition

In: MRS Proceedings, Jg. 1230E (2010), S. 3-5
Zeitschriftenaufsatz / Fach: Physik
Fakultät für Physik » Experimentalphysik
Large amplitude coherent optical phonons have been investigated in laser-excited Bismuth by means of femtosecond time-resolved X-ray diffraction. For absorbed laser fluences above 2 mJ/cm2, the experimental data reveal an extreme softening of the excited A1g-mode down to frequencies of about 1 THz, only 1/3 of the unperturbed A1g-frequency. At even stronger excitation the measured diffraction signals no longer exhibit an oscillatory behavior presenting strong indication that upon intense laser-excitation the Peierls-distortion, which defines the equilibrium structure of Bismuth, can be transiently reversed.