ToF-SIMS profiling of Fe impurities in LaAlO3/SrTiO3

Complex oxides host many emergent phenomena which appear in heterostructures but not the bulk materials. LaAlO3 and SrTiO3 are both nonmagnetic complex oxides. Yet, there are many reports of magnetism at the LaAlO3/SrTiO3(LAO/STO) interface [1,2], but no clear indication about its origin. Here we describe time-of-flight secondary ion mass spectrometry (ToF-SIMS) experiments to search for magnetic impurities at the LAO/STO interface. We find an abundance of Fe located within a few nanometers of the LAO/STO interface in two LAO/STO samples, while measurements on two other LAO/STO samples show no presence of Fe. We discuss these results in the context of what is known and reported in the LAO/STO system.

[1] Brinkman, A., et al. Nature Materials 6, 493-496 (2007)

[2] Pai, Yun-Yi, et al. 2019. In Spintronics Handbook: Spin Transport and Magnetism, Second Edition, 2nd Edition, 489–517. CRC Press.