Thermal Transport in Weakly Coupled Spin-1/2 Heisenberg-Ladders

We investigate the weakly coupled spin-1/2 Heisenberg ladder in the low energy limit. As magnetic excitations significantly contribute to the thermal transport, we expose the ladder to a magnetic field and analyze the thermal conductivity and the specific heat capacity depending on the magnetization.

Starting point is the spin-1/2 Heisenberg chain and its fermionic and bosonic description by conformal field theory. From coupling two spin chains and applying the (rescaled) bosonisation technique, a free theory for spin-ladders and its spectrum is obtained. Special interest lies on the conformal anomaly and the Tomonaga-Luttinger Liquid parameters. Introducing temperature to the theory gives access to the thermal transport properties.