Anisotropic spin-orbit scattering of hot-electron spins injected into ferromagnetic thin films

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 Ni80Fe20, independent of temperature. The corresponding scattering time (<0.3 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.