Paper published in Journal of Applied Physics: “Contributions of electron and phonon transport to the thermal conductivity of gdfeco and tbfeco amorphous rare-earth transition-metal alloys”

Our paper, “Contributions of electron and phonon transport to the thermal conductivity of gdfeco and tbfeco amorphous rare-earth transition-metal alloys,” was recently published in the Journal of Applied Physics (J. Appl. Phys. 111, 103533 (2012)).  In this work, we quantify the electron and phonon contributions to thermal conductivity of amorphous rare-earth transition-metal alloys, a class of material systems that is widely used in magneto-optical recording media.  We measure the thermal conductivity of thin films of GdFeCo and TbFeCo with time domain thermoreflectance.  Thought electrical resistivity measurements, we separate the contribution of electron and phonon transport to thermal conductivity in these materials.  We show that the phonon contribution in these amorphous metals is substantial, and accounts for the majority of the thermal conduction in these materials from 80 – 400 K. This work was performed in collaboration with Professor Joe Poon in the Physics Department at U.Va.

Abstract

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.

This work was funded by NSF (CBET Award #1134311)