Investigations on the origin of ferromagnetism in Ga1−xCrxN and Si-doped Ga1−xCrxN films: Experiments and theory.

In this paper, we combined experiments and first-principles calculations to investigate the physical properties especially the magnetic properties of Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N thin films grown by molecular beam epitaxy. The results of experiments indicate that Si doping improved the crystallinity by improving the substitution of Ga in Si-doped Ga 1−x Cr x N. And the size and/or the number of vacancy defects are reduced in the Si-doped Ga 1−x Cr x N thin films. All the samples show room-temperature ferromagnetism, and the measured saturation magnetizations are 15 emu/cm 3 (2.26 μ B per Cr atom) and 10 emu/cm 3 (1.31 μ B per Cr atom) respectively for Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N thin films. First-principles calculations based density-functional theory show that there is a strong magnetic coupling between the Ga vacancies and the impurities of Cr and Si ions. And Si doping reduced the saturation magnetization in Si-doped Ga 1−x Cr x N thin films which is in agreement with the experiment results. This intrinsic defect derived magnetic interaction plays an important role on improving the ferromagnetism in Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N, and the ferromagnetism of the system is the result of long-range mediation between V Ga , Cr and Si ions. [ABSTRACT FROM AUTHOR]