Anomalous Thermal Conductivity of Frustrated Heisenberg Spin Chains and Ladders

Abstract

We study the thermal transport properties of several quantum spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. The temperature at which the non-diverging prefactor κ (th) (T ) peaks is in general substantially lower than the temperature at which the corresponding specific heat cV (T ) is maximal. We show that this result of the microscopic approach leads to a substantial reduction for estimates of the magnetic mean-free path λ extracted by analyzing recent experiments, as compared to similar analyses by phenomenological theories.

Comment on “Anomalous Thermal Conductivity of Frustrated Heisenberg Spin Chains and Ladders”

“…This will be corroborated by supplementary data for systems up to N = 18 sites. In Figs [1], the overall decrease of C(N ) remains clearly observable, except for minor finite-size oscillations, which, however, justify no extrapolation to a finite value for N → ∞.…”

“…In this Comment, we argue that, from the systems investigated in [1], no conclusions of a finite thermal Drude weight in the gapped regime of frustrated chains for N → ∞ can be drawn. This will be corroborated by supplementary data for systems up to N = 18 sites.…”

“…In a recent Letter [1], Alvarez and Gros have presented a numerical study of the thermal conductivity of frustrated chains and spin ladders with spin 1/2. Using exact diagonalization of finite systems with N ≤ 14 sites, they have computed the zero-frequency weight κ (th) (T, N ), i.e., the Drude weight, of the thermal conductivity where T is the temperature and N the number of sites.…”

“…In the latter case, this conclusion is based on a finite-size analysis of the high-temperature residue C(N ), given by lim T →∞ [T 2 κ (th) (T, N )] = C(N ), for α = 0.1, 0.24, 0.35 (see Refs. [1,2] for definitions; also note [3]).…”

Transport in one dimensional quantum systems

“…Furthermore, the experimental observation of unusually high thermal conductivity in ladder compounds [1] motivated the theoretical study of the thermal Drude weight in 1D anisotropic, frustrated and ladder spin-1/2 systems [68,69]; the proposal of unconventional thermal transport in these systems is still debated.…”