Nickelate heterostructures as a laboratory for many-body physics

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Multilayers with precisely controlled interfaces between two different materials can give rise to novel physical phenomena and functionalities not exhibited by either of the constituents alone, like the quantum Hall effect in semiconductor multilayers and the “giant magnetoresistance” in multilayers of simple metals. Interfaces between transition-metal oxides can exhibit properties not observed at semiconductor or ordinary metal interfaces, such as emergent superconductivity and ferromagnetism, opening a path towards a new generation of electronic devices. In this project, multilayers and superlattices based on nickelates with perovskite structure will be synthesized with atomic precision using pulsed-laser deposition, and investigated with resonant X-ray linear/circular dichroism and reflectometry, spectral ellipsometry, aberration-corrected high-resolution transmission electron microscopy (ACHRTEM) and electron energy loss spectroscopy (EELS). The goal of this investigation is a detailed understanding of the relationship between the atomic structure and the electronic properties at the interfaces, with particular focus on the valence states, orbital occupation, and charge transport. The electronic interactions at the interface will then be manipulated in a controlled fashion by varying the thickness and chemical composition of the constituent layers, the strain imposed by the substrate, and the concentration of defects. Ultimately, we strive to realize new quantum phases, including a high-temperature superconducting phase predicted in prior theoretical work.