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TT: Tiefe Temperaturen
TT 21: Metall Isolatorüberg
änge
TT 21.3: Talk
Thursday, March 29, 2001, 10:00–10:15, J
Thermoelectric transport properties in amorphous materials at the metal-insulator transition — •Cristine Villagonzalo1, Rudolf A. Römer1, Michael Schreiber1, and Angus MacKinnon2 — 1Institut für Physik, Technische Universität, D-09107 Chemnitz — 2Blackett Laboratory, Imperial College, London SW7 2BZ, U.K.
First, we study the behavior of the thermal transport properties in three-dimensional disordered systems close to the metal-insulator transition within linear response [1]. Using a suitable form for the energy-dependent conductivity σ, we show that the value of the dynamical scaling exponent for noninteracting disordered systems such as the Anderson model of localization can be reproduced. Furthermore, the values of the thermoelectric power S have the right order of magnitude close to the transition as compared to the experimental results. A sign change in S — as is often observed in experiments — can also be modeled within the linear response formulation using modified experimental σ data as input. Furthermore, we show that the temperature dependent σ, S, the thermal conductivity K and the Lorenz number L0 obey scaling [2].
Next, we use the Green’s function recursive method to microscopically determine the thermoelectric transport properties without assuming a functional form of the energy-dependent σ. Preliminary investigations on a one-dimensional wire show that the distribution of the Peltier coefficient is Lorentzian for localized states.
[1] C. Villagonzalo, et. al, to be published in Phys. Rev. B 62 (2000).
[2] C. Villagonzalo, et. al, in Proc. 25th Int. Conf. on the Physics of Semiconductors, Osaka 2000, (to be published January 2001).