Exploring Correlated Topological States with Charge Density Waves
Abstract
Combining strong electron-phonon coupling and relativistic electrons offers new ground states and associated emergent excitations, such as topological superconductivity, axion insulators, extreme mobility, and magneto-resistance. However, it has been difficult to find systems where correlations, disorder, carrier density, topology, and electron-phonon coupling are independently tuned. unambiguously determining the role of each in the novel physical responses, let alone the deterministic emergence of new phenomena, has proven exceedingly difficult. These materials also offer important advances relevant to DOD and AFOSR, namely via their high mobility, topologically nontrivial carriers, and their controllable phases. Of particular interest are charge density waves that are inherently nonlinear and switchable. As such fine tuning these materials could enable new nonlinear devices, including switches, memories, and compact IR detectors of the polarization state. However, successful implementation of topological semimetals in devices, as with the creation of new phases, requires a systematic approach in a material system where each component is adjusted and measured separately. The proposed program addressed this need by using recent advances of the co-PIs in revealing systems where charge density waves (CDW) and magnetism co-exist in a Dirac semimetal, along with the use of Raman and nonlinear photocurrents to probe changes in crucial excitations and Berry connection. The co-PI already revealed several new states and phenomena, including a Devil s staircase and Axial Higgs mode from combining the CDW and quantum geometry. The effort builds on these advances, focusing on the controlled tuning of the materials. We will better understand the interplay between symmetry, electron-phonon coupling, electronic structure, magnetism, and topology to create new correlated-topological phases and experimental procedures that reveal their unique signatures.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410110
Entities
People
- Kenneth Burch
Organizations
- Air Force Office of Scientific Research
- Boston College
- United States Air Force