Melting of a Wigner crystal in an ionic dielectric
Laboratoire d'Études des Propriétés Électroniques des
Solides CNRS, BP 166, 38042 Grenoble Cedex 9, France
Published online: 15 March 2000
The melting of a Wigner Crystal of electrons placed into a host polar material is examined as a function of the density and the temperature. When the coupling to the longitudinal optical modes of the host medium is turned on, the WC is progressively transformed into a polaronic Wigner crystal. We estimate the critical density for crystal melting at zero temperature using the Lindeman criterion. We show that above a certain critical value of the Fröhlich electron-phonon coupling, the melting towards a quantum liquid of polarons is not possible, and the insulator-to-metal transition is driven by the ionization of the polarons (polaron dissociation). The phase diagram at finite temperature is obtained by making use of the same Lindeman criterion. Results are also provided in the case of an anisotropic electron band mass, showing that the scenario of polaron dissociation can be relevant in anisotropic compounds such as the superconducting cuprates at rather moderate e-ph couplings.
PACS: 71.30.+h – Metal insulator transitions and other electronic transitions / 71.38.+i – Polarons and electron-phonon interactions / 71.10.-w – Theories and models of many electron systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000