  We theoretically study the nonlocal spin transport in a device consisting of
a nonmagnetic metal (N) and ferromagnetic injector (F1) and detector (F2)
electrodes connected to N. We solve the spin-dependent transport equations in a
device with arbitrary interface resistance from a metallic-contact to tunneling
regime, and obtain the conditions for efficient spin injection, accumulation,
and transport in the device. In a device containing a superconductor (F1/S/F2),
the effect of superconductivity on the spin transport is investigated. The
spin-current induced spin Hall effect in nonmagnetic metals is also discussed.
