Attosecond XUV Probing of Carrier and Spin Dynamics in Materials and at Interfaces
Abstract
Previous research in this AFOSR program was based on ultrafast photoelectron spectroscopy at surfaces and interfaces. During the program the research shifted to measurements with attosecond transient absorption methodology. The program uses attosecond transient absorption (and reflection) in the extreme ultraviolet (XUV) to investigate carrier and phonon dynamics in solid-state materials and transport of carriers across junctions. The program in the last grant period also completed important work on hypergolic ionic liquid ignition, a collaboration with Steven Chambreau and Ghanshyam (Gammy) Vaghjiani of AFRL. One comprehensive part of the completed experimental research is on carrier dynamics in metal dichalcogenide films, investigating hot carrier cooling, core-level exciton decays, and coherent phonon motion. Another aspect of the work is on the very rapid thermalization of hot electrons in metals. Another type of measurement is on transport of carriers across junctions. A final aspect of the completed research involves mechanisms of coherent phonon excitation, specifically the anticorrelation between hot carriers and phonon excursion and the mechanisms that play a role during the initial approach to coherent phonon motion. One of the main goals of the future work is to measure and understand spin relaxation, specifically relaxation of spin-aligned holes in semiconductor materials, metals, two-dimensional metal dichalcogenides, and quantum dots. Another important aspect of the proposed work is the transfer of spin and magnetism across junctions in several classes of materials, such as ferromagnetic - paramagnetic as well as magnetic quantum dots. Introduction of circular dichroism into attosecond transient absorption and transient reflectivity brings a new dimension that allows important fundamental principles of spin relaxation and transport to be assessed with element-specific sensitivity.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410184
Entities
People
- Stephen R. Leone
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of California Regents