Magnon drag effect in Fe-Co alloys

摘要

We report here a systematic study of the magnon-drag induced thermoelectric properties of Fe-rich, Fe-Co body-centered-cubic alloys. The sign of the low temperature behavior of thermopower is explained well by the hydrodynamic theory for magnon-drag, informed by density functional theory calculations of the ground state of Fe-Co alloys. The high-temperature thermopower of some of the alloys, and indeed that of elemental iron, changes the sign, as previously observed. We propose a mechanism to elucidate this hitherto unexplained observation. Further, the power factor of Fe72Co28 peaks around 35 mu V/cm K-2 at 500 K, comparable to the standard thermoelectric material Bi2Te3. Because of their high thermoelectric power factor, Fe-Co alloys are potential candidate thermoelectric metals for active cooling of electronic devices.