Probing the physics of complex oxide interfaces with scanning SQUID microscopy
Complex oxide materials have a broad range of functionality such as ferromagnetism,piezoelectricity, and superconductivity. When combinations of complex oxides are grown as heterostructures, changes in the local electronic-structure at the interface can create new electronic phases that cannot exist in either parent material. One example is the interface formed by growing LAO on STO. Though both materials are non magnetic insulators, the interface between them shows conductivity, superconductivity and even magnetism.
In the LAO/STO system we found nanoscale patches of magnetism coexisting with superconductivity. I will describe our efforts to understand this magnetism, by mapping the landscape of ferromagnetism, superconductivity and conductivity with scanning SUQID microscopy. I will focus on viewing the local distribution of current flow at the interface, where we found that the current flow is enhanced on conductive channels that are related to STO tetragonal domain structure. The interplay between substrate domains and the interface provides an additional mechanism for understanding and controlling the behaviors of heterostructures.