Elliott-Yafet Mechanism And The Discussion Of Femtosecond Magnetization Dynamics

In the past it has been questioned whether the Elliott-Yafet mechanism of spin-flip scattering of electrons at phonons may explain the ultrafast demagnetization of a ferromagnet (mostly Ni) after femtosecond laser excitation. The reason has been that the value of the Elliott-Yafet spin-mixing parameter b(2) of Ni has not been known and has been taken as the one of Cu (which is the nearest neighbor in the periodic table) which is very small. We present calculations of b(2) by the ab initio density-functional electron theory for Co, Fe, Ni, Cu, Au, and K. For Co, Fe, and Ni b(2) is about a factor of 25 larger than the value commonly assumed for Cu. This result should support the Elliott-Yafet mechanism in the discussion of fs magnetization dynamics.