Controlling Fundamental Physical Interactions in Strongly-Correlated and Two-Dimensional Electronic Systems with Ultrafast THz Electric Fields
Abstract
Major Goals: This project aims at addressing the grand scientific challenges related to emergence and control of electronic, magnetic and structural phases of matter in strongly-correlated materials, heterostructures and two- dimensional electronic systems. Our main goal is to develop a fundamental understanding of the three-dimensional nanoscale evolution of materials properties governed by the flow of energy and angular momentum as the electronic and magnetic states are driven out of equilibrium by external stimuli. Within this framework, we are focusing on two specific physical phenomena that are of key importance to our fundamental understanding of phase transitions and emergence and thus are also of great interest to logic and memory device science: (1) Ferroelectric control of interface conductivity in Mott insulators (such and CaMnO3), and (2) Electric-field control of interface magnetism in oxide/alloy heterojunctions (such as FeRh/BaTiO3). As an exploratory aspect of these two research directions, we plan expand our technical expertise with the above mentioned materials (CaMnO3, FeRh and BaTiO3) to the static and time-resolved investigations of similar technologically-relevant systems wherein interface and two-dimensional (including topological) phenomena play a defining role. Examples of such systems may include other strongly-correlated perovskite oxides, transition-metal dichalcogenides and topological insulators. By applying novel x-ray spectroscopic and scattering techniques to the studies of emergent phenomena in prototypical magnetic, strongly-correlated and two-dimensional electronic systems we expect to answer the following fundamental questions that are universally applicable to the nanoscale physics of ultrafast phase transitions and collective excitations: 1. How fast and on what characteristic length scales do the new electronic, magnetic and structural phases emerge and evolve in materials and heterojunctions in the presence of intense electromagnetic fields? 2. What happens to the electronic structure of a strongly-correlated material or a two-dimensional system that is driven into a new phase by an intense electric-field pulse during the first picosecond of the transition before the lattice has time to react? 3. Does a new electronic phase of matter emerge as a homogeneous phase, or does the electronic structure spatially de-phase into regions which can be resolved via x-ray scattering and/or imaging techniques? 4. If the latter is true, do the regions containing the new electronic phase emerge near the interfaces and/or structural defect sites, or is the spatial phase separation a fundamental requirement for the phase transition? We believe that the answers to these questions will provide decisive insights into the nature of collective electronic and structural rearrangements responsible for the nanoscale phase-transition physics. Finally, ultrafast electric-field control of electronic ordering, collective modes, and spin excitations at the interfaces between materials that are already highly functional promises technological advances that could take the modern technology beyond the realm of semiconductor heterostructure physics.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Dec 04, 2018
- Source ID
- W911NF1510181
Entities
People
- A. X. Gray
Organizations
- Army Contracting Command
- Temple University
- United States Army