Magnetic and optical properties of the InCrN system

Room-temperature ferromagnetic $In1−xCrxN$ films with $x$ ranging from 0.0005 to 0.04 and antiferromagnetic CrN films have been grown by plasma-assisted molecular-beam epitaxy. Electron and x-ray-diffraction techniques could find no evidence for precipitates or phase segregation within the films. Ferromagnetism was observed in the $In1−xCrxN$ layers over a wide range of Cr concentrations, with the magnitude of the ferromagnetism found to correlate with the background carrier concentration. Higher $n$-type carrier concentrations were found to lead enhanced ferromagnetism, with maximum saturation and remnant moments of 7 and $0.7emu∕cm3$⁠, respectively. The addition of Cr to the InN matrix led to reduced photoluminescence intensity and a shift of the peak to higher energy. These observations along with a band-gap-like optical transmission feature at 0.7 eV suggest that CrN has an indirect gap of approximately 0.7 eV and a direct $Γ$-valley gap greater than 1.2 eV.