Theory of charge density wave depinning by electromechanical effect
Résumé
We discuss the first theory for the depinning of low dimensional, incommensurate, charge densitywaves (CDWs) in the strong electron-phonon (e-p) regime. Arguing that most real CDWs systemsinvariably develop a gigantic dielectric constant (GDC) at very low frequencies, we propose anelectromechanical mechanism which is based on a local field effect. At zero electric field and largeenough e-p coupling the structures are naturally pinned by the lattice due to its discreteness, anddevelop modulation functions which are characterized by discontinuities. When the electric fieldis turned on, we show that it exists a finite threshold value for the electric field above which thediscontinuities of the modulation functions vanish due to CDW deformation. The CDW is thenfree to move. The signature of this pinning/depinning transition as a function of the increasingelectric field can be directly observed in the phonon spectrum by using inelastic neutrons or X-rays experiments
Domaines
Optique [physics.optics]
Origine : Fichiers produits par l'(les) auteur(s)
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