Femtosecond electron and spin dynamics in Ni/W(110) films.

摘要: The collapse of the magnetic exchange splitting in 7 monolayer thick epitaxial $\mathrm{N}\mathrm{i}/\mathrm{W}(110)$ films following a femtosecond laser pulse was measured using time-resolved photoemission spectroscopy. Ultrafast demagnetization during induced hot electron cascade proceeds via spin-flip excitations with relaxation time constant $300\ifmmode\pm\else\textpm\fi{}70\text{ }\mathrm{f}\mathrm{s}$. At longer times electronic system cools down and magnetization is finally reestablished $3.2\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{p}\mathrm{s}$.