  We theoretically study the spin-polarized transport through a single-molecule
magnet, which is weakly coupled to ferromagnetic leads, by means of the
rate-equation approach. We consider both the ferromagnetic and
antiferromagnetic exchange-couplings between the molecular magnet and
transported electron-spin in the nonlinear tunneling regime. For the
ferromagnetic exchangecoupling, spin current exhibits step- and basin-like
behaviors in the parallel and antiparallel configurations respectively. An
interesting observation is that the polarization reversal of spin-current can
be realized and manipulated by the variation of bias voltage in the case of
antiferromagnetic exchange-coupling with antiparallel lead-configuration, which
may be useful in the development of spintronic devices, while the bias voltage
can only affect the magnitude of spin-polarization in the ferromagnetic
coupling.
