Magnetic effects at the interface between nonmagnetic oxides

TL;DR

This paper demonstrates that magnetic properties can be induced at the interface between nonmagnetic oxides SrTiO3 and LaAlO3, revealing magnetic hysteresis and negative magnetoresistance, thus offering new insights into interface magnetism in oxides.

Contribution

It shows how magnetic effects can be generated at nonmagnetic oxide interfaces, expanding the understanding of interface-induced magnetism in perovskite oxides.

Findings

Large negative magnetoresistance observed

Logarithmic temperature dependence of sheet resistance

Magnetic hysteresis at low temperatures

Abstract

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.