  We have studied growth and properties of quaternary alloy magnetic
semiconductor (InGaMn)As grown both on GaAs substrates and on InP substrates by
low-temperature molecular-beam epitaxy (LT-MBE). (InGaMn)As thin films were
ferromagnetic below ~30 K, exhibiting strong magneto-optical effect. The
lattice constant of [(InyGa1-y)1-xMnx]As, whose Mn concentration x is below 4%,
is slightly smaller than that of InyGa1-yAs with the same In/Ga content ratio.
We have also obtained very smooth surface morphology of nearly lattice matched
(InGaMn)As thin films grown on InP substrates, which is important for
application to thin-film type magneto-optical devices integrated with III-V
opto-electronics.
