We have employed combinatorial approach to explore molecular beam epitaxy synthesis and characterization of multicomponent magnetic alloys. Structural evolution was studied in situ using scanning reflection high-energy electron diffraction and magnetic properties were probed using magneto-optic imaging and SQUID magnetometry. Results from a ternary system of CoMnGe are presented. These alloys exhibit a rich variety of magnetic and magneto-optic behavior, including a robust phase near Co0.4Mn0.4Ge0.2 with high-spin polarization, high T-c and high magneto-optic response. The observed magnetic responses show strong correlation with structural trans formations such that structural ordering and symmetry change can give rise to enhanced magnetic and magneto-optic interactions. The observed magnetism in these alloys and their compatibility with Ge substrates make them potential candidates for spin electronic transport studies and applications. (C) 2002 Published by Elsevier Science B.V.