1. X-ray study of femtosecond structural dynamics in the 2D charge density wave compound 1T-TaS2
- Author
-
Benoit Corraze, Sylvain Ravy, T. Huber, Claire Laulhé, Andrés Ferrer, Gabriel Lantz, S. Grübel, A. Lübcke, Steven L. Johnson, Paul Beaud, S. Boulfaat, Etienne Janod, S. O. Mariager, Laurent Cario, Gert L. Ingold, Jeremy A. Johnson, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Chimie Physique - Matière et Rayonnement (LCPMR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Universidad Nacional de Córdoba [Argentina], and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
Diffraction ,Phase transition ,Materials science ,Photon ,Condensed matter physics ,Phase (waves) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Molecular physics ,Electronic, Optical and Magnetic Materials ,Amplitude ,0103 physical sciences ,Femtosecond ,[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] ,Electrical and Electronic Engineering ,010306 general physics ,0210 nano-technology ,Charge density wave ,ComputingMilieux_MISCELLANEOUS ,Excitation - Abstract
1T-TaS2 is a 2D metallic compound which undergoes a series of electronically driven phase transitions toward charge density wave and Mott phases. Its intricate electron–phonon interactions and electron–electron correlations have been promising peculiar out-of-equilibrium dynamics. In this paper, we provide the first direct information on the atomic structure response to an ultra-fast infrared laser pulse in the commensurate phase of 1T-TaS2, by using femtosecond time-resolved X-ray diffraction. We show that ultra-fast excitation with near-infrared photons drives a displacive excitation of the amplitude mode of the commensurate charge density wave. About 3 ps after laser excitation, the system reaches a new, photo-induced state that is maintained for at least 10 ps. We give evidence that this long-lived state exhibits the same structural modulation as in the thermodynamically stable commensurate phase, with a large correlation length. Only the average amplitude of the modulation is found to decrease. We propose that the long-lived state is formed from the commensurate phase by reducing the modulation amplitude on few superlattice nodes. The underlying mechanism proposed is the annihilation of self-trapped polarons.
- Published
- 2015