From quantum-CCD to continuum-K3: Atomic-resolution STEM-EELS studies of perovskite oxide films and membranes

In the field of perovskite oxide research, STEM-EELS is now a vital analytical technique, owing to its potential for not just characterizing elemental composition but also probing of bonding and valence states at scales down to that of the atomic column. In this talk, I will discuss various ways that we have utilized STEM-EELS to study perovskite oxide films and membranes, in the context of our ongoing collaboration with the Department of Quantum Matter Physics at the University of Geneva. Examples will include the mapping of electronic state in rare earth nickelate superlattices and alloys, that we are now extending to in-situ measurements across the metal-to-insulator transition point, and recent work on writing crystalline interfaces between strontium titanate membranes and substrates using the STEM electron beam. At the same time, I will illustrate the improvements made, and analytical possibilities opened, by switching our EELS detection system from a Gatan Quantum with CCD camera to a Continuum with K3 direct electron detection, together with taking a look at a couple of challenges that the latter system brings.