Signature of electron-magnon Umklapp scattering in <i>L</i>1₀ FePt probed by thermoelectric measurements

We report unconventional thermoelectric power (Seebeck coefficient, S) in L10 structured FePt films. The temperature dependence of S can be well fitted by a phenomenological expression consisting electron diffusion and magnon-drag contributions. Interestingly, the magnon drag coefficient carries an opposite sign to that diffusion, revealing dominant contribution from elusive electron-magnon Umklapp scattering. Density-functional theory calculations identify several bands crossing Brillouin zone boundaries, facilitating process. large spin–orbit coupling results strong mixing majority minority spins among some those bands, greatly enhancing