III–V based magnetic(GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices

III–V based magnetic (GaMnAs)/nonmagnetic(AlAs) semiconductor superlattices (SLs) have been grown by low-temperature molecular beam epitaxy. X-ray diffraction measurements show that the SLs have good crystalline quality and abrupt interfaces. The SLs having relatively wide (Ga,Mn)As layers (⩾70 Å) are found to be ferromagnetic at low temperatures, while the SLs with narrow (Ga,Mn)As layers (⩽50 Å) are paramagnetic even at 2.0 K. Magneto-optic spectra have revealed that, due to the quantum confinement effect, the interband transition energy at Γ is blue shifted with decreasing the thickness of the (Ga,Mn)As and some subbands are formed.