Volume 117, Number 5, March 2017
|Number of page(s)||7|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||04 May 2017|
Theory of charge density wave depinning by electromechanical effect
Institut Néel, CNRS and Université Grenoble-Alpes - BP 166, 38042 Grenoble Cedex 9, France
Received: 15 February 2017
Accepted: 7 April 2017
We discuss the first theory for the depinning of low-dimensional, incommensurate, charge density waves (CDWs) in the strong electron-phonon (e-p) regime. Arguing that most real CDWs systems invariably develop a gigantic dielectric constant (GDC) at very low frequencies, we propose an electromechanical mechanism which is based on a local field effect. At zero electric field and large enough e-p coupling the structures are naturally pinned by the lattice due to its discreteness, and develop modulation functions which are characterized by discontinuities. When the electric field is turned on, we show that it exists a finite threshold value for the electric field above which the discontinuities of the modulation functions vanish due to CDW deformation. The CDW is then free to move. The signature of this pinning/depinning transition as a function of the increasing electric field can be directly observed in the phonon spectrum by using inelastic neutrons or X-rays experiments.
PACS: 71.45.Lr – Charge-density-wave systems / 63.20.kd – Phonon-electron interactions / 77.65.-j – Piezoelectricity and electromechanical effects
© EPLA, 2017
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