The non-universality of critical conductance in quantum site-percolation

✍ Scribed by A Kusy; A.W. Stadler; G Hałdaś; R Sikora

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 309 KB
• Volume: 50
• Category: Article
• ISSN: 0042-207X
• DOI: 10.1016/s0042-207x(98)00045-1

✦ Synopsis

The conductance in the quantum site-percolation on simple cubic lattice is numerically studied using

Landauer-Biittiker formalism. Binary distribution of site energies P(E,) =pb(~,,)+(l-p)d(~,,--co) is assumed with p(l-p) being concentration of metallic (insulating) sites. The metal-insulator transition is defined as such point pq for which dimensionless conductance g changes its dependence on linear size L of the system from g CC exp (--L&J for p < pq to g cc L for p > pq. The critical conductance at the metal-insulator transition is estimated as gC = g (p,). It is found that g, expressed in e2/PI units decreases from 1 at the center of each subband (EN = 0) down to 0.002 in the vicinity of the subband edge (E/U = 6). This, almost three orders of magnitude, variation of the critical conductance vs electron Fermi energy E can be compared with the range 0.02-10.0 obtained for gC by Kaveh and Mott.' They have concluded that critical conductance is not universal. Our data support this conclusion.