Münster 1999 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 21: Postersitzung III: Hochfrequenzeigenschaften (1-4), Amorphe Systeme (5-9), Borkarbide (10-18), Quantenflüssigkeiten (19-25), Dünne Filme (26-49), Vortexdynamik, Pinning (50-63), M-I-Überg
änge, quantenkritische Ph
änomene (64-89)
TT 21.78: Poster
Donnerstag, 25. März 1999, 14:30–18:00, Foy
The Thermoelectric Power of Disordered Systems near the Anderson Transition — •C. Villagonzalo, R. A. Römer, and M. Schreiber — Institut für Physik, Technische Universität, D-09107 Chemnitz
We investigate the behavior of the thermoelectric power S in disordered
systems close to the Anderson-type metal-insulator transition (MIT) at low
temperatures. Theoretical studies [1, 2] have either argued that S
diverges [1] or it remains a constant [2] as the localization transition
is approached. These studies employ the Chester-Thellung-Kubo-Greenwood
formulation of linear response. In Ref. 1, the chemical potential µ
is taken to be at the Fermi energy EF at finite temperature T and
then T→0 is taken. Moreover, the d.c. conductivity σ
near the Anderson transition is treated as a slowly varying function of the
energy. However, for the Anderson transition this is not the case. Also,
µ=EF holds true only at T=0. Hence, Enderby and Barnes [2] considered
µ to be at the mobility edge EC and took the limit T→0.
To address this problem, we calculate the T-dependence of µ directly
from the number density n of electrons at the MIT. We calculate the value
of n at the MIT in disordered systems using an averaged density of states
obtained by diagonalizing the three-dimensional Anderson model of localization.
Without any additional approximation, we thus obtain the behavior of S
at low T as the Anderson transition is approached from the metallic side.
We show that indeed S does not diverge.
[1] U. Sivan and Y. Imry, Phys. Rev. B 33, 551 (1986); C.
Castellani, C. Di Castro, M. Grilli, and G. Strinati, Phys. Rev. B 37, 6663 (1988).
J. E. Enderby and A.C. Barnes, Phys. Rev. B
49, 5062 (1994).