Thermal conductivity of the four-leg spin-ladder system La2Cu2O5 single crystal

We have investigated the magnetic susceptibility, chi, and the thermal conductivity, kappa, in magnetic fields for the four-leg spin-ladder system La2Cu2O5 single crystal. The chi in a magnetic field parallel to the ladder exhibits a kink at 130 K in correspondence to the magnetic ordering. The kappa along the ladder exhibits a peak at 25 K and a shoulder at 14 K, which are probably related to the thermal conductivity due to magnons, kappa(magnon), and that due to phonons, kappa(phonon), respectively. The kappa perpendicular to the ladder, on the other hand, exhibits only one broad peak related to kappa(phonon). The observed large anisotropy of kappa has been explained based upon the anisotropy of kappa(magnon).