Contributions of electron and phonon transport to the thermal conductivity of GdFeCo and TbFeCo amorphous rare-earth transition-metal alloys

We experimentally investigate the electron and phonon contributions to the thermal conductivity of amorphous GdFeCo and TbFeCo thin films. These amorphous rare-earth transition-metal (RE-TM) alloys exhibit thermal conductivities that increase nearly linearly with temperature from 90 to 375 K. Electrical resistivity measurements show that this trend is due to an increase in the electron thermal conductivity over this temperature range and a relatively constant phonon contribution to thermal conductivity. We find that at low temperatures (∼90 K), the phonon systems in these amorphous RE-TM alloys contribute ∼70% to thermal conduction with a decreasing contribution as temperature is increased.