Magnetism tuned by the charge states of defects in bulk C-doped SnO2 materials

Abstract

To analyze the controversial conclusions on the magnetism of C-doped SnO₂ (SnO₂:C) bulk materials between theoretical calculations and experimental observations, we propose the critical role of the charge states of defects in the geometric structures and magnetism, and carry out a series of first principle calculations. By changing the charge states, we can influence Bader charge distributions and atomic orbital occupancies in bulk SnO₂:C systems, which consequently conduct magnetism. In all charged SnO₂:C supercells, C-2p_x/p_y/p_z electron occupancies are significantly changed by the charge self-regulation, and thus they make the C-2p orbitals spin polarized, which contribute to the dominant magnetic moment of the system. When the concentration of C dopant in the SnO₂ supercell increases, the charge redistribution assigns extra electrons averagely to each dopant, and thus effectively modulates the magnetism. These findings provide an experimentally viable way for controlling the magnetism in these systems.