Starts 1 Feb 2008 11:00
Ends 1 Feb 2008 20:00
Central European Time
Main Building Seminar Room
Strada Costiera, 11 I - 34151 Trieste (Italy)
Insulators close to the metal insulator transition exhibit interesting collective electronic phenomena which are still rather poorly understood. A prominent feature in such systems is the purely electronic nature of activated transport apparent in experiments, which is inconsistent with the theory of phonon-assisted hopping conduction and thus has remained an unexplained puzzle for decades. The situation became even less clear when recently theories of many body localization predicted a metal insulator transition at finite temperature for interacting electrons that are decoupled from phonons. In this talk I will address this problem for Anderson insulators with a single-particle localization length much larger than the mean distance between electrons. Under these circumstances Coulomb interactions drive the electrons into a strongly correlated quantum glass phase with non-trivial collective behavior. I will show that a typical metastable state exhibits a gapless spectrum of collective excitations which act as a bath with which individual electrons can exchange energy. In 2D systems, this results in a hopping transport mechanism with a nearly universal pre-exponential factor of order e2/h. This is in good agreement with many recent experiments.
  • M. Poropat