Ballistic heat transport in nanocontacts

We have determined the ballistic heat transport relation of V2 =C (Tm -T) in nanocontacts involving the bias voltage V, the ambient temperature T, and the maximum temperature Tm inside the contact by exploiting the ordering temperature of a magnetic solid as a natural thermometer. The relation has been further established using a single contact at one temperature but different magnetic fields. A simple energy-transfer model incorporating ballistic transport can qualitatively account for this relation. We also demonstrate a ballistic transport method for determining the ordering temperatures of magnets.