Theoretical calculations of the valence-band electron states in a two-dimen
sional quantum well (QW) with diluted magnetic semiconductor barriers are p
erformed in the case of in-plane external magnetic field B. Cases of relati
vely weak and strong magnetic fields should be discriminated. In the first
case the barrier continuum spectrum is separated from localized heavy- and
light-hole states in st QW. In the case of a strong enough magnetic field,
the superimposition of a barrier continuum spectrum on light-hole QW levels
can take place due to the giant spin splitting of semimagnetic semiconduct
or band states. Moreover, the strong mixing between quantum-confined and ba
rrier states takes place due to the nonconservation of angular momentum in
an inclined magnetic field. This results in the transformation of light-hol
e-localized states in a QW to resonant (virtual) ones. We use a Luttinger m
odel with a symmetric rectangular potential to recapture the transition fro
m localized to resonant states with an increasing external magnetic field B
. Calculations of electron-hole optical transitions show a broadening of op
tical lines and a shift of their maxima. The considered situation is shown
to be easily realized in the structures Cd1-xMnxTe/CdTe/Cd1-xMnxTe. [S0163-
1829(99)15231-7].