Jianan Li: Magneto-optical Kerr probing of LAO/STO interface ferromagnetism

Interfacial ferromagnetism in LaAlO3/SrTiO3 (LAO/STO) heterostructures has been probed by a variety of techniques. Recently, magnetic force microscopy (MFM) was used to image ferromagnetic domains that are electrically tunable at room temperature when the samples were grown in certain conditions. Optical techniques provide powerful tools for probing magnetic phenomena, and recently magnetic circular dichroism has been observed in reduced bulk STO crystals. Here we describe a scanning magneto-optical Kerr imaging system that could achieve sub-micrometer precision and 10−4 rad/√ Hz sensitivity with a 150 fs pulsed-laser centered at 425 nm. Such capability would make pump and probe measurement on the gate-tunable LAO/STO ferromagnetism and ultrafast imaging of domain dynamics possible.