Defect-induced magnetism in SiC: The new opportunity in spintronics

The charge and spin are two intrinsic properties of electron. Electronic devices mainly utilize the charge of electrons, while mass storage devices are based on the spin of electrons. Diluted magnetic semiconductors provide the opportunity to use the charge and spin of electrons simultaneously, which may bring revolutionary changes in the information technology. Progresses have been achieved in the preparation of magnetic wide band-gap semiconductors with Curie temperatures at around room temperature by dopings. However, limited solubility of transition metals often leads to the precipitation of second phases, thwarting the attempts to get the unambiguous experimental results. Recently, there has been increasing evidence that traditional magnetic elements are not the sole source in inducing intrinsic magnetism. The effect of defects on magnetism formation is gradually being realized.
Our work has been focusing on the origin of magnetism in SiC for many years. Early research demonstrated that Mn is not the only source to determine the magnetic ordering in Mn doped SiC. Subsequently, ferromagnetism was induced in SiC by non-TM element Al dopings. Based on the results mentioned above, we carefully investigated the magnetism of neutron irradiated / noble gas ion implanted SiC single crystals in a series of work. The results unambiguously verified that defects can induce magnetism. The intentionally created defects dominated by divacancies (VSiVC) are responsible for the observed magnetism. The long-range ferromagnetic coupling can be attributed to the p electrons of the nearest-neighbor carbon atoms around VSiVC. Besides, the concentration of VSiVC has an optimal value and excess defects will depress the magnetism.