Ferromagnetic Relaxation by the Exchange Interaction between Ferromagnetic Electrons and Conduction Electrons

Abstract

The Hamiltonian for the exchange interaction between the ferromagnetic $d$ electrons and the conduction $s$ electrons is derived. The ferromagnetic relaxation time caused by the $s\ensuremath{-}d$ exchange interaction is calculated in a spin wave approximation. When one uses a screened value of the exchange integral ($\frac{{J}_{\mathrm{atomic}}}{30}$), the calculated relaxation time for nickel at room temperature is 5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec as compared to the time 2.5\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ sec needed to account for the experimental line width. The exchange relaxation may be dominant in materials such as alloys which have narrower lines than nickel.