Anisotropic spin-orbit scattering of hot-electron spins in ferromagnets is examined by injecting a hot-electron current into the thin ferromagnetic base of a transistor and measuring the current attenuation as a function of the magnetization orientation. The transmission anisotropy is described by a simple model, from which we extract an effective spin-orbit scattering length of 420 nm for hot-electron spins in ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$, independent of temperature. The corresponding scattering time ( $<0.3\mathrm{}\mathrm{ps}$) is surprisingly short, suggesting efficient spin-lattice relaxation of hot electrons. The results also unambiguously demonstrate the attenuation of a hot-electron current by an elastic scattering process.

• Received 21 March 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.166601