Effects of spin accumulation on single-electron tunneling in a double ferromagnetic microjunction

Electron tunneling in a double microjunction, in which one electrode is nonmagnetic while the second electrode and metallic island are ferromagnetic, is analysed theoretically in the Coulomb blockade regime. The limit of fast intrinsic spin relaxation on the island (no spin accumulation) is compared with the limit of slow spin relaxation (maximum spin accumulation). It is shown that spin accumulation leads to a strong dependence of the Coulomb "staircase" on the magnetic configuration of the junction and, consequently, to a number of new effects.