Pump-probe ARPES for Studies of Electron and Phonon Dynamics in Novel Materials

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Nontechnical abstract Utilizing a newly developed time-resolved angle-resolved photoemission ARPES system, the dynamics of electron interactions in a variety of important classes of materials will be determined. The focus will be on "correlated electron" systems including high transition temperature superconductors and charge density wave systems, in which the electronic interactions or correlations are especially important. The general goal and the basis of the intellectual merit of the project will be to determine the dynamics of various excited states of a solid and ultimately to control these processes through suitably tailored ultrafast optical pump pulses. These goals directly relate to two grand challenges: "How do remarkable properties of matter emerge from complex correlations of the atomic or electronic constituents and how can we control these properties?" and "How can matter be characterized and controlled away from - especially very far away - from equilibrium?". In addition to the scientific impacts discussed above, the intimate inclusion of students in this research program is emphasized as it is one of the most effective ways to attract talented undergraduates and retain them in careers in science and engineering. Four undergraduate research students are currently working on projects related to this program. The PI will also expand upon a set of active outreach projects, which will include education and outreach over the full range from middle-school students to advanced researchers and professionals. Technical abstract Utilizing a newly developed time-resolved angle-resolved photoemission ARPES (trARPES) system, the dynamics of electron interactions in a variety of important classes of materials will be determined. The focus will be on "correlated electron" systems including high transition temperature superconductors, charge density wave systems, and Mott insulators. trARPES is still in its infancy, though the power of this new technique is clear because it brings the powers of ARPES together with the field of ultrafast spectroscopy and coherent control. The new system includes a number of advantages compared to previous trARPES systems, including a) improved energy resolution while staying at or near the time-bandwidth limit. b) Improved selectivity and control in how the system is pumped, including wide tunability of photon energies as well as high pump power, giving the possibility for tailored resonant pumping of charges and phonons. The trARPES experiments will be closely coupled with static (single photon) laser and synchrotron-ARPES experiments performed in the same group on similar or identical materials. In addition to the scientific impacts discussed above, the intimate inclusion of students in this research program is emphasized as it is one of the most effective ways to attract talented undergraduates and retain them in careers in science and engineering. Four undergraduate research students are currently working on projects related to this program. The PI will also expand upon a set of active outreach projects, which will include education and outreach over the full range from middle-school students to advanced researchers and professionals.