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 10.12.2010   Карта сайта     Language По-русски По-английски
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Статистика публикаци


10.12.2010

Snapshots of cooperative atomic motions in the optical suppression of charge density waves





Journal name:

Nature

Volume:

468,

Pages:

799–802

Date published:

(09 December 2010)

DOI:

doi:10.1038/nature09539


Received


Accepted


Published online







Macroscopic quantum phenomena such as high-temperature superconductivity, colossal magnetoresistance, ferrimagnetism and ferromagnetism arise from a delicate balance of different interactions among electrons, phonons and spins on the nanoscale1. The study of the interplay among these various degrees of freedom in strongly coupled electron–lattice systems is thus crucial to their understanding and for optimizing their properties. Charge-density-wave (CDW) materials2, with their inherent modulation of the electron density and associated periodic lattice distortion, represent ideal model systems for the study of such highly cooperative phenomena. With femtosecond time-resolved techniques, it is possible to observe these interactions directly by abruptly perturbing the electronic distribution while keeping track of energy relaxation pathways and coupling strengths among the different subsystems3, 4, 5, 6, 7. Numerous time-resolved experiments have been performed on CDWs8, 9, 10, 11, 12, 13, probing the dynamics of the electronic subsystem. However, the dynamics of the periodic lattice distortion have been only indirectly inferred14. Here we provide direct atomic-level information on the structural dynamics by using femtosecond electron diffraction15 to study the quasi two-dimensional CDW system 1T-TaS2. Effectively, we have directly observed the atomic motions that result from the optically induced change in the electronic spatial distribution. The periodic lattice distortion, which has an amplitude of ~0.1Å, is suppressed by about 20% on a timescale (~250 femtoseconds) comparable to half the period of the corresponding collective mode. These highly cooperative, electronically driven atomic motions are accompanied by a rapid electron–phonon energy transfer (~350 femtoseconds) and are followed by fast recovery of the CDW (~4 picoseconds). The degree of cooperativity in the observed structural dynamics is remarkable and illustrates the importance of obtaining atomic-level perspectives of the processes directing the physics of strongly correlated systems.





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А Б В Г Д Е Ё Ж З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Ъ Ы Ь Э Ю Я
  • Chen Wev .  honorary member of ISSC science council

  • Harton Vladislav Vadim  honorary member of ISSC science council

  • Lichtenstain Alexandr Iosif  honorary member of ISSC science council

  • Novikov Dimirtii Leonid  honorary member of ISSC science council

  • Yakushev Mikhail Vasilii  honorary member of ISSC science council

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