The excitonic insulator route through a dynamical phase transition induced by an optical pulse
- Université Paris-Saclay, LPS, CNRS, Univ. Paris-sud (France)
We consider a dynamical phase transition induced by a short optical pulse in a system prone to thermodynamical instability. We address the case of pumping to excitons whose density contributes directly to the order parameter. To describe both thermodynamic and dynamic effects on equal footing, we adopt a view of the excitonic insulator for the phase transition and suggest a formation of the Bose condensate for the pumped excitons. The work is motivated by experiments in donor–acceptor organic compounds with a neutral- ionic phase transition coupled to the spontaneous lattice dimerization and to charge transfer excitons. The double nature of the ensemble of excitons leads to an intricate time evolution, in particular, to macroscopic quantum oscillations from the interference between the Bose condensate of excitons and the ground state of the excitonic insulator. The coupling of excitons and the order parameter also leads to self-trapping of their wave function, akin to self-focusing in optics. The locally enhanced density of excitons can surpass a critical value to trigger the phase transformation, even if the mean density is below the required threshold. The system is stratified in domains that evolve through dynamical phase transitions and sequences of merging. The new circumstances in experiments and theory bring to life, once again, some remarkable inventions made by L.V. Keldysh.
- OSTI ID:
- 22617317
- Journal Information:
- Journal of Experimental and Theoretical Physics, Vol. 122, Issue 3; Other Information: Copyright (c) 2016 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BOSE-EINSTEIN CONDENSATION
CONDENSATES
DENSITY
DIMERIZATION
EXCITONS
FOCUSING
GROUND STATES
INSTABILITY
INTERFERENCE
INVENTIONS
OPTICAL PUMPING
OPTICS
ORDER PARAMETERS
ORGANIC COMPOUNDS
OSCILLATIONS
PHASE TRANSFORMATIONS
PULSES
THERMODYNAMICS
WAVE FUNCTIONS