  The electronic reconstruction at the interface between two insulating oxides
can give rise to a highly-conductive interface. In analogy to this remarkable
interface-induced conductivity we show how, additionally, magnetism can be
induced at the interface between the otherwise nonmagnetic insulating
perovskites SrTiO3 and LaAlO3. A large negative magnetoresistance of the
interface is found, together with a logarithmic temperature dependence of the
sheet resistance. At low temperatures, the sheet resistance reveals magnetic
hysteresis. Magnetic ordering is a key issue in solid-state science and its
underlying mechanisms are still the subject of intense research. In particular,
the interplay between localized magnetic moments and the spin of itinerant
conduction electrons in a solid gives rise to intriguing many-body effects such
as Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions, the Kondo effect, and
carrier-induced ferromagnetism in diluted magnetic semiconductors. The
conducting oxide interface now provides a versatile system to induce and
manipulate magnetic moments in otherwise nonmagnetic materials.
