  Thermal switching provides an effective way for active heat flow control,
which has recently attracted increasing attention in terms of nanoscale thermal
management technologies. In magnetic and spintronic materials, the thermal
conductivity depends on the magnetization configuration: this is the
magneto-thermal resistance effect. Here we show that an epitaxial
Cu/Co$_{50}$Fe$_{50}$ multilayer film exhibits giant magnetic-field-induced
modulation of the cross-plane thermal conductivity. The magneto-thermal
resistance ratio for the Cu/Co$_{50}$Fe$_{50}$ multilayer reaches 150% at room
temperature, which is much larger than the previous record high. Although the
ratio decreases with increasing the temperature, the giant magneto-thermal
resistance effect of ~100% still appears up to 400 K. The magnetic field
dependence of the thermal conductivity of the Cu/Co$_{50}$Fe$_{50}$ multilayer
was observed to be about twice greater than that of the cross-plane electrical
conductivity. The observation of the giant magneto-thermal resistance effect
clarifies a potential of spintronic multilayers as thermal switching devices.
