Spin accumulation in ferromagnetic single-electron transistors

We propose a new method of direct detection of spin accumulation, which overcomes difficulties met in earlier measurements. A spin dependent current in a single-electron transistor with ferromagnetic electrodes leads to a nonequilibrium spin accumulation on the metallic island. Owing to the charging energy, the resulting spin-splitting of the electrochemical potential of the island can be detected from the spacing between two resonances in the current–voltage characteristics. The effect can be observed both in the sequential and cotunneling limits.