Regensburg 2004 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 24: Postersitzung III: Korrelierte Elektronen, ”Orbital Physics”
TT 24.15: Poster
Mittwoch, 10. März 2004, 14:30–19:00, Poster A
Finite temperature Drude weight of strongly correlated 1d systems — •Stefan Glocke and Andreas Klümper — Universität Wuppertal, Theoretische Physik, Gauß-Straße 20
We present results for the Drude weight Ds of the spin conductivity σ of the integrable spin-1/2 XXZ chain at arbitrary temperature (σ = electrical conductivity in the spinless fermion language of the model). The results are obtained by a combination of linear response theory (Kubo formula) and solution techniques of Bethe ansatz type. Unlike the case of thermal conductivity, the state of investigation of the spin conductivity of the XXZ chain is less complete if not controversial. The reason for this lies in the non-conservation of the spin (charge) current. Despite this, there is a delta-function peak at zero frequency in the dynamical conductivity σ(ω)=Ds ·δ(ω)+σreg(ω). The controversies of [1],[2] and more recent treatments arise about the anisotropy (interaction) and temperature dependence of Ds. Some of the controversies are resolved by the observation of a strong variation of the energy level curvatures even within a microcanonical ensemble between “very similar states”.
[1] B.N. Narozhny, A.J. Millis, N. Andrei: Phys. Rev. B 58, R2921 (1998)
[1] X. Zotos: Phys. Rev. Lett. 82, 1764 (1999)