A.L. Efros speaking this afternoon

[Cond.Matt. & Stat.Mech.Section]

SEMINAR on       Disorder and strong electron correlations

 

Wednesday, 18 July -  4:00 p.m.

 

Luigi Stasi Seminar Room,  Leonardo Building - first floor


 
Alexei L. EFROS     ( University of Utah, Salt Lake City )

 

" Electron glass "



Abstract

An electron glass (EG) is a disordered film with localized electronic states and hopping conduction.  It has a long time relaxation (hours and days), that usually manifests itself in the slow change of the hopping conduction. Moreover, they may have a memory. Namely, conductivity of the film as a function of the electron density memorizes the density at which it has been cooled. Disordered films of InxO [1], films granulated by gold [2] or aluminum [3] are examples of EG’s. Important low energy excitations in such a system can be classified as single electron excitations that feature the so-called Coulomb Gap, and pair excitations that are random dipoles [4]. I argue that the polarization of dipole interactions leads to a “polarization catastrophe” due to interaction of these excitations. As a result dipoles form a dipole glass [5]. I propose that this is at the basis of glassy properties of the system. The width of the “memory dip” is calculated.

1. M Ben-Chorin, D. Kowal, and Z. Ovadyahu, Phys. Rev. B44, 342 (1991).

2. C.J. Adkins et al. J. Phys. C17, 4693 (1984).

3. T. Grenet, Eur. Phys. J. B32, 275 (2003).

4. A.L. Efros and B.I. Shklovskii, J. Phys. C8, L 49 (1975).

5. B.E. Vugmeister and M.D. Glinchuk, Rev. Modern Phys. 62, 993 (1990).