  Spin-polarized current through an Al nanoparticle in tunnel contact with two
ferromagnets is measured as a function of the direction of the applied magnetic
field. The nanoparticle filters the spin of injected electrons along a
direction specified by the magnetic field. The characteristic field scale for
the filtering corresponds to a lower limit of $8ns$ for the spin-dephasing
time. Spin polarized current versus applied voltage increases stepwise,
confirming that the spin relaxation time is long only in the ground state and
the low-lying excited states of the nanoparticle.
