Size-dependent induced magnetism in carbon-doped ZnO nanostructures

The role of quantum confinement on the carbon doped ZnO nanocrystals will be examined using a real-space, first-principles method. We find that the spin polarization energy of carbon defects in nanocrystals is sensitive to size owing to the partial occupancy of a less-localized minority spin state. In addition, we find that the partial occupancy of a minority spin state results in a direct exchange mechanism between the carbon defects even under strong confinement. The analysis suggests that the semiconductor with non-magnetically induced magnetic moments should provide a significant advantage over the traditional dilute magnetic semiconductors when applied to nanometer-scaled applications.