| AVS 59th Annual International Symposium and Exhibition | |
| Actinides and Rare Earths Focus Topic | Monday Sessions |
| Session AC+MI+SS+TF-MoM |
| Session: | Electronic Structure and Spectroscopy of Actinides |
| Presenter: | T. Durakiewicz, Los Alamos National Laboratory |
| Correspondent: | Click to Email |
Every time we add a new dimension to an experimental method, we open a window to novel, unexpected and fascinating phenomena. Here we show the results of our focused effort of adding time-domain to the powerful experimental techniques of Angle Resolved Photoelectron Spectroscopy (ARPES) and reflectivity. The novel tools are applied to actinides and help us understand the details of the electronic structure of the correlated f-electron materials.
In the hidden order system URu2Si2 we investigate the massive renormalization of the Fermi surface at specific k values. The application of time-resolved ARPES allowed a direct measurement of the momentum-resolved quasiparticle lifetime which was shown to increase by an order of magnitude at the hidden order transition. Time-resolved ARPES together with the ultrafast reflectivity results provided evidence for forming a multiple gap structure, including the hybridization gap, pseudogap and HO gap [1, 2].
Another actinide system of interest is a Mott insulator UO2, where we have investigated the complex dynamics of the Hubbard excitons. We have found that the dynamics can be divided into four distinct processes: instantaneous hop, picosecond lattice deformation, phonon emission and relaxation, and the slow relaxation related to the propagation of Hubbard excitons [3]. We have also obtained the first direct measurement of Hubbard gap in 5f system [4].
The novel femtosecond pump-probe methods provide unique information about the dynamics of 5f quasiparticles, and open novel possibilities in addressing the long-standing questions about the role of near-Fermi level band renormalization in establishing the physical properties of correlated materials.
References
[1] Physical Review B 84, 161101(Rapid Comm.) (2011)
[2] Physical Review B 84, 161103(Rapid Comm.) (2011)
[3] Physical Review Letters 106, 207402 (2011)
[4] manuscript in preparation