  We study the non-collinear exchange coupling across a trilayer magnetic
junction consisting of two ferromagnets separated by a thin dilute magnetic
semiconductor containing itinerant carriers with finite spin relaxation. It is
remarkable that, by increasing the spin relaxation, the critical temperature is
substantially enhanced and the shape of the magnetization curve becomes more
mean-field like. We attribute these interesting changes to the broken
time-reversal symmetry which suppresses the oscillatory
Ruderman-Kittel-Kasuya-Yosida interaction. Our argument is further strengthened
by the emergence of the non-collinear spiral exchange coupling across the
trilayer magnetic junction with finite spin relaxation.
