Thermally-activated relaxation of the magnetization in the Dy-Sc nitride clusterfullerene Dy₂ScN@C₈₀-I_h proceeds via the fifth-excited Kramers doublet with the energy barrier of 1735 K.

We present experimental results for the thermal conductivity $\kappa$ of the pseudo-two-leg ladder material ${\mathrm{CaCu}}_2{\mathrm{O}}_3$. The strong buckling of the ladder rungs renders this material a good approximation to a $S=1/2$ Heisenberg chain. Despite a strong suppression of the thermal conductivity of this material in all crystal directions due to inherent disorder, we find a dominant magnetic contribution ${\kappa }_{\mathrm{mag}}$ along the chain direction. ${\kappa }_{\mathrm{mag}}$ is linear in temperature, resembling the low-temperature limit of the thermal Drude weight $D_{\mathrm{th}}$ of the $S=1/2$ Heisenberg chain. The comparison of ${\kappa }_{\mathrm{mag}}$ and $D_{\mathrm{th}}$ yields a magnetic mean-free path of $l_{\mathrm{mag}}\approx 22\pm 5\AA$, in good agreement with magnetic measurements.