Defect-Induced Magnetism in Solids

In recent years, the number of nominally nonmagnetic solids showing magnetic order induced by some kind of defect has increased continuously. From the single element material graphite to several covalently bonded nonmagnetic compounds, the influence of defects like vacancies and/or nonmagnetic ad-atoms on triggering magnetic order has attracted the interest of experimentalists and theoreticians. We review and discuss the main theoretical approach as well as recently obtained experimental evidence based on different experimental methods that support the existence of defect-induced magnetism in nonmagnetic as well as in magnetic materials.