Zero-dimensional spin accumulation and spin dynamics in a mesoscopic metal island

We have measured electron spin accumulation at 4.2 K and at room temperature in an aluminum island with all dimensions (400 nmx400 nmx30 nm) smaller than the spin relaxation length. For the first time, we obtain uniform spin accumulation in a four-terminal lateral device with a magnitude exceeding the Ohmic resistance in the island. By controlling the magnetization directions of the four magnetic electrodes that contact the island, we have performed a detailed study of the spin accumulation. Spin precession measurements confirm the uniformity of our system and provide an accurate method to extract the spin relaxation time.