NSF/DMR-BSF: Spatially Resolved Probes of Magnetism at Oxide Interfaces

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

Nontechnical abstract: Some of the most remarkable discoveries are related to the existence and nature of magnetism, and magnetism at a non-magnetic interface remains one of the greatest outstanding mysteries of modern physics. Experimental evidence has revealed magnetism coexisting with superconductivity, and the existence of magnetism at room temperature. This project seeks to provide understanding of such unexpected phenomena. The research requires proficiency in a variety of areas including physics, materials science, and nanoscale engineering, making it challenging and rewarding for beginning graduate and undergraduate students. Students also receive valuable training and experience in an international research setting: this research project is made possible by an international collaboration with a research team from the Weizmann Institute in Israel and exposes students both scientifically and culturally. Technical abstract: The interface between two insulating oxides, strontium titanate and lanthanum aluminate, exhibits an incredibly rich palette of emergent behavior. Some of the most remarkable discoveries have related to the existence and nature of magnetism, which coexists at low temperature with superconductivity, and is strongly influenced by the density of mobile electrons at the interface. Fundamental questions about the origin and nature of magnetism at (non-magnetic) oxide interfaces are investigated using a suite of probes that combine high spatial and temporal resolution. This project seeks an increased understanding of coupled phases in oxides, greatly benefiting the oxide community as a whole. The research focuses on developing a microscopic understanding of the origin of magnetism at oxide interfaces, with a particular emphasis on the role of both localized and delocalized electrons that are otherwise confined to these interfaces. This research combines ultrasensitive probes of magnetism at low temperature with the ability to create electronic nanostructures using conductive-atomic fore microscope lithography. A variety of complementary imaging techniques are employed to reveal magnetic properties at the oxide interface, including magnetic force microscopy , time resolved Kerr rotation, and superconducting-quantum-interference-device-on-a-tip microscopy. This unique combination of techniques, made possible by an international collaboration between the United States and Israel, is able to provide new insights into the most important outstanding physics questions concerning this remarkable material system.