  Magnetic order at room temperature induced by atomic lattice defects, like
vacancies, interstitials or pairs of them, has been observed in a large number
of different nonmagnetic hosts, such as pure graphite, oxides and silicon-based
materials. High Curie temperatures and time independent magnetic response at
room temperature indicate the extraordinary robustness of this new phenomenon
in solid state magnetism. In this work, we review experimental and theoretical
results in pure TiO$_2$ (anatase), which magnetic order can be triggered by
low-energy ion irradiation. In particular, we discuss the systematic
observation of an ultrathin magnetic layer with perpendicular magnetic
anisotropy at the surface of this oxide.
