Magnetism in 2D BN1−x_{1-x}Ox_x and B1−x_{1-x}Six_xN: polarized itinerant and local electrons

We use density functional theory based first-principles methods to study the magnetism in a 2D hexagonal BN sheet induced by the different concentrations of oxygen and silicon atoms substituting for nitrogen (O$_\mathrm{N}$) and boron (Si$_\mathrm{B}$) respectively. We demonstrate the possible formation of three distinct phases based on the magnetization energy calculated self-consistently for the ferromagnetic (ME$_{\mathrm{FM}}$) and antiferromagnetic (ME$_{\mathrm{AFM}}$) states, i.e. the paramagnetic phase with ME$_{\mathrm{FM}}$=ME$_{\mathrm{AFM}}$, the ferromagnetic phase with ME$_{\mathrm{FM}}$$>$ME$_{\mathrm{AFM}}$ and finally the polarized itinerant electrons with finite ME$_{\mathrm{FM}}$ but zero ME$_{\mathrm{AFM}}$. While the O$_\mathrm{N}$ system was found to exist in all three phases, no tendency towards the formation of the polarized itinerant electrons was observed for the Si$_\mathrm{B}$ system though the existence of the other two phases was ascertained. The different behavior of these two systems is associated with the diverse features in the magnetization energy as a function of the oxygen and silicon concentrations. Finally, the robustness of the polarized itinerant electron phase is also discussed with respect to the O substitute atom distributions and the applied strains to the system.Comment: accepted by RP

Solution and testing of the Abraham-Minkowski controversy in light-atom interacting system

We present the origin of the Abraham-Minkowski controversy of light-matter wave interacting system, which is a special case of the centaury-old Abraham-Minkowski controversy. We solve the controversy of laser-atom interacting case and find that for systems with perfect atomic spatial coherence, the systems prefer to show Minkowski momentum and canonical momentum for the atoms and light, respectively; while for the systems where the atoms are spatially incoherent, the momenta of light and atoms would choose the Abraham and kinetic forms. The provement of our solution can be realized with current techniques, using three-dimensional optical lattices and electromagnetically-induced absorption (EIA) to distinguish the kinetic and canonical recoil momentum of ultra-cold atoms.Comment: 4 pages, 3 figure