ABSTRACT
We present a numerical study on the spin and thermal conductivities of the spin-1 Heisenberg chain in the high temperature limit, in particular, the Drude weight contribution and frequency dependence. We use the exact diagonalization and the recently developed microcanonical Lanczos method; it allows us a finite size scaling analysis by the study of significantly larger lattices. This work, pointing to a diffusive rather than ballistic behavior, is discussed with respect to other recent theoretical and experimental studies.
ABSTRACT
Based on numerical simulations, a study of the high temperature, finite frequency, thermal conductivity kappa(omega) of spin-1/2 ladders is presented. The exact diagonalization and a novel Lanczos technique are employed. The conductivity spectra, analyzed as a function of rung coupling, point to a nondiverging dc limit but to an unconventional low frequency behavior. The results are discussed in perspective with recent experiments indicating a significant magnetic contribution to the energy transport in quasi-one-dimensional compounds.
ABSTRACT
The zero temperature Hall constant R(H), described by reactive (nondissipative) conductivities, is analyzed within linear response theory. It is found that in a certain limit R(H) is directly related to the density dependence of the Drude weight, implying a simple picture for the change of sign of charge carriers in the vicinity of a Mott-Hubbard transition. This novel formulation is applied to the calculation of R(H) in quasi-one-dimensional and ladder prototype interacting electron systems.
