Thermal transport anomaly associated with weak ferromagnetism in CaMnO3

The thermal conductivity kappa(T), thermal diffusivity alpha(T) and magneti zation M(T) have been measured for sintered CaMnO3 and La1-xCaxMnO3 in ligh tly electron-doped region (0.98 less than or equal to x less than or equal to 1.0). kappa(T) and alpha(T) of CaMnO3 show an anomalous enhancement belv w the weak ferromagnetic transition temperature T-N. The enhancement is rap idly reduced by introduction of a small amount of Mn3+ ions in La1-xCaxMnO3 . The analyses suggest the possibility that the enhancement comes from the contribution of the heat transport by magnetic excitations.