  The notion of decoupling of spin and charge currents is one of the basic
principles underlying the rapidly expanding feld of Spintronics. However, no
direct demonstration of the phenomenon exists. We report a novel measurement,
in which a non-equilibrium spin population is created by a point-like injection
of current from a ferromagnet across a tunnel barrier into a one dimensional
spin channel, and detected differentially by a pair of ferromagnetic electrodes
placed symmetrically about the injection point. We demonstrate that the spin
current is strictly isotropic about the injection point and, therefore,
completely decoupled from the uni-directional charge current.
