Speaker: Jay Ram Paudel, Temple University
Program Description:
The emergence of phenomena at oxide interfaces has recently captured significant scientific attention owing to the advancement of atomically precise techniques for synthesizing high-quality thin films. In this presentation, I will systematically investigate these phenomena within oxide heterostructures, employing various X-ray spectroscopic and scattering techniques. Specifically, I will focus on examining CaMnO3/LaNiO3 and CaMnO3/CaRuO3 superlattices. The metal-to-insulator transitions and interfacial ferromagnetism, induced by charge transfer, render CaMnO3/LaNiO3 superlattices an ideal platform for studying diverse electronic and magnetic phenomena. To delve into the electronic and magnetic properties of these superlattices, we conducted measurements using X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD), and hard X-ray photoemission spectroscopy (HAXPES). XAS and HAXPES provide depth-averaged insights into these properties. In our pursuit of depth-resolved electronic and magnetic profiles within these superlattices, we harnessed standing-wave photoemission spectroscopy (SW-XPS) and X-ray resonant magnetic reflectometry (XRMR). As for the CaMnO3/CaRuO3 superlattice, our XRMR measurements uncovered an asymmetric magnetic moment at the top and bottom interfaces. Subsequent first-principle calculations suggested that oxygen vacancies were likely responsible for this magnetic asymmetry. Furthermore, I will briefly show our ongoing measurements, including spin-resolved ARPES and Momentum Microscopy, as part of our group's future research prospects.
