  We investigate ballistic spin transport in a two dimensional electron gas
system through magnetic barriers of various geometries using the transfer
matrix method. While most of the previous studies have focused on the effect of
magnetic barriers perpendicular to the two dimensional electron gas plane, we
concentrate on the case of magnetic barriers parallel to the plane. We show
that resonant oscillation occurs in the transmission probability without
electrostatic potential modulation which is an essential ingredient in the case
of ordinary out-of-plane magnetic barriers. Transmission probability of the
in-plane magnetic barrier structure changes drastically according to the number
of barriers and also according to the electrostatic potential modulation
applied in the magnetic barrier region. Using a hybrid model consisting of a
superconductor, ferromagnets, and a two dimensional electron gas plane, we show
that it can serve as a good in-plane oriented spin selector which can be
operated thoroughly by electrical modulation without any magnetic control.
