We consider electron tunneling in ferromagnetic single-barrier and double-b
arrier planar junctions. The single-barrier junctions include additional th
in films at the electrode/barrier interfaces. In the case of double-barrier
systems, electron tunneling is considered in both sequential and coherent
tunneling regimes. Generally, all components of the junctions, including ex
ternal and central electrodes, thin metallic films and barriers can be ferr
omagnetic. We present numerical results for the following junctions: (i) si
ngle-barrier junctions with nonmagnetic barrier and nonmagnetic electrodes,
but with thin ferromagnetic metallic films on both sides of the barrier; (
ii) double-barrier junctions with ferromagnetic external electrodes and non
magnetic barriers and central electrode; (iii) double-barrier junctions wit
h ferromagnetic barriers and nonmagnetic central and external electrodes. (
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