What makes an insulator different from a metal?

Дата и время публикации : 2000-03-01T17:40:40Z

Авторы публикации и институты :
Raffaele Resta

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 12 pages with 3 figures. Presented at the workshop “Fundamental Physics of Ferroelectrics”, Aspen Center for Physics, February 2000
Первичная категория: cond-mat.mtrl-sci

Все категории : cond-mat.mtrl-sci, cond-mat.str-el

Краткий обзор статьи: The insulating state of matter is characterized by the excitation spectrum, but also by qualitative features of the electronic ground state. The insulating ground wavefunction in fact: (i) displays vanishing dc conductivity; (ii) sustains macroscopic polarization; and (iii) is localized. The idea that the insulating state of matter is a consequence of electron localization was first proposed in 1964 by W. Kohn. I discuss here a novel definition of electron localization, rather different from Kohn’s, and deeply rooted in the modern theory of polarization. In fact the present approach links the two features (ii) and (iii) above, by means of essentially the same formalism. In the special case of an uncorrelated crystalline solid, the localization of the many-body insulating wavefunction is measured – according to our definition – by the spread of the Wannier orbitals; this spread diverges in the metallic limit. In the correlated case, the novel approach to localization is demonstrated by means of a two-band Hubbard model in one dimension, undergoing a transition from band insulator to Mott insulator.

Category: Physics