Interview for Faculty Position

Magnetism of LaAlO₃/SrTiO₃ Heterostructure Interface

Lu Li

MIT

The LaAlO₃/SrTiO₃ heterostructure is a potential candidate for a high mobility two-dimensional electron system with novel electronic and magnetic properties. Though LaAlO₃ and SrTiO₃ are both large-gap band insulators, the interface is conductive, and even superconducting below 200 mK. Magnetic ordering has been proposed to arise from the d-electrons transferred by polarization discontinuity. However the magnetization of this system has not previously been studied, due to the small volume of the interface. Using torque magnetometry, we detect the magnetic moment of the interface system directly. Our results indicate the existence of a magnetic ordering at the two-dimensional conductive interface. More importantly, the same magnetic behavior persists even when the sample is superconducting, which suggests an unconventional superconducting phase.