THERMAL-CONDUCTIVITY OF THE SPIN-PEIERLS COMPOUND CUGEO3

The thermal conductivity kappa of the spin-Peierls (SP) compound CuGeO 3 was measured in magnetic fields up to 16 T. Above the SP transition, the heat transport due to spin excitations causes a peak ar similar t o 22 K, while below the transition the spin excitations rapidly dimini sh and the heat transport is dominated by phonons; however, the main s cattering process of the phonons is with spin excitations, which demon strates itself in an unusual peak in kappa at similar to 5.5 K. This l ow-temperature peak is strongly suppressed with magnetic fields in exc ess of 12.5 T.