Direct measurement of spin-dependent conduction-electron mean free paths in ferromagnetic metals

Using a new giant magnetoresistance structure we measure the spin-up mean free paths of ferromagnetic metals. At room temperature we find for Co λ+=55±4, for Fe λ+-15±2, and for Ni80Fe20 alloy λ+=46±3. Combining these results with the Mott picture of transport we deduce the spin-down mean free paths, and find for Co λ-6 , for Fe λ-=21±5, and for Ni80Fe20 λ-6 . © 1993 The American Physical Society.