Hamburg 2001 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 20: Niederdimesnionale Systeme, Magnetotransport, Quantenhalleffekt II
TT 20.2: Vortrag
Donnerstag, 29. März 2001, 09:45–10:00, A
Multiparticle Exchange in the Wigner Crystal and Wigner Glass — •Klaus Voelker1, Hoang Nguyen2, and Sudip Chakravarty2 — 1ETH Zürich — 2University of California, Los Angeles
We consider a two-dimensional electron system at zero temperature and low carrier densities, where the long-range Coulomb interactions dominate over the kinetic energy. In this classical limit the clean system will form a Wigner crystal state with long-range structural order. Quantum mechanical corrections arise in the form of multiparticle exchange processes. This allows one to express the effective Hamiltonian in the form of electron (or spin) permutation operators. Disorder will destroy the Wigner crystal on large length scales, and the resulting state is called a Wigner glass. Short-range structural order will remain, however, so that the notion of multiparticle exchange processes is still applicable. As a first step towards characterizing the magnetic properties of the system we calculate numerically the exchange frequencies for all dominant processes. In the Wigner glass the exchange frequencies follow a random distribution. Our primary goal is to quantify this distribution as a function of disorder strength, and to draw conclusions about the influence of disorder on the magnetic properties of the Wigner glass.