A team of researchers has discovered that magnetism can be induced at the interface between two nonmagnetic insulating perovskites, SrTiO₃ and LaAlO₃. This finding is significant because it shows that magnetic moments can be created at the interface through electronic reconstruction, leading to a highly conductive interface with a large negative magnetoresistance. The magnetoresistance is temperature-dependent, showing a logarithmic dependence of the sheet resistance and magnetic hysteresis at low temperatures. The magnetic effects are attributed to spin scattering of conduction electrons off localized magnetic moments at the interface, which is a key mechanism in solid-state physics. The study also highlights the role of oxygen vacancies in oxide interfaces, which can lead to conduction. However, in the case of the SrTiO₃-LaAlO₃ interface, the magnetic effects are not due to oxygen vacancies but rather to the polar discontinuity at the interface. This polar discontinuity leads to the formation of localized magnetic moments on the Ti site, which can scatter conduction electrons and give rise to magnetic effects. The researchers used a combination of experimental techniques, including atomic force microscopy (AFM), x-ray diffraction, and x-ray photoelectron spectroscopy (XPS), to characterize the interface and confirm the presence of magnetic moments. The sheet resistance was measured using a Van-der-Pauw geometry, and the magnetoresistance was found to be large, up to 30%, over a magnetic field range of 30 T. The magnetoresistance was found to be independent of the orientation of the magnetic field relative to the interface, indicating that the effect is related to spin physics rather than orbital effects. The study also shows that the temperature dependence of the sheet resistance is logarithmic, which is consistent with the Kondo effect, which describes the interplay between localized magnetic moments and mobile charge carriers. The Kondo temperature was found to be around 70 K, and the observed energy scale was comparable to the energy scale of the magnetoresistance effects. The findings suggest that the interface between SrTiO₃ and LaAlO₃ can be used as a versatile system to induce and manipulate magnetic moments in otherwise nonmagnetic materials. This could have important implications for the development of all-oxide devices with carrier-controlled ferromagnetism. The study also highlights the importance of understanding the interplay between localized magnetic moments and itinerant conduction electrons in solid-state systems.A team of researchers has discovered that magnetism can be induced at the interface between two nonmagnetic insulating perovskites, SrTiO₃ and LaAlO₃. This finding is significant because it shows that magnetic moments can be created at the interface through electronic reconstruction, leading to a highly conductive interface with a large negative magnetoresistance. The magnetoresistance is temperature-dependent, showing a logarithmic dependence of the sheet resistance and magnetic hysteresis at low temperatures. The magnetic effects are attributed to spin scattering of conduction electrons off localized magnetic moments at the interface, which is a key mechanism in solid-state physics. The study also highlights the role of oxygen vacancies in oxide interfaces, which can lead to conduction. However, in the case of the SrTiO₃-LaAlO₃ interface, the magnetic effects are not due to oxygen vacancies but rather to the polar discontinuity at the interface. This polar discontinuity leads to the formation of localized magnetic moments on the Ti site, which can scatter conduction electrons and give rise to magnetic effects. The researchers used a combination of experimental techniques, including atomic force microscopy (AFM), x-ray diffraction, and x-ray photoelectron spectroscopy (XPS), to characterize the interface and confirm the presence of magnetic moments. The sheet resistance was measured using a Van-der-Pauw geometry, and the magnetoresistance was found to be large, up to 30%, over a magnetic field range of 30 T. The magnetoresistance was found to be independent of the orientation of the magnetic field relative to the interface, indicating that the effect is related to spin physics rather than orbital effects. The study also shows that the temperature dependence of the sheet resistance is logarithmic, which is consistent with the Kondo effect, which describes the interplay between localized magnetic moments and mobile charge carriers. The Kondo temperature was found to be around 70 K, and the observed energy scale was comparable to the energy scale of the magnetoresistance effects. The findings suggest that the interface between SrTiO₃ and LaAlO₃ can be used as a versatile system to induce and manipulate magnetic moments in otherwise nonmagnetic materials. This could have important implications for the development of all-oxide devices with carrier-controlled ferromagnetism. The study also highlights the importance of understanding the interplay between localized magnetic moments and itinerant conduction electrons in solid-state systems.