Interaction of pulsed laser fields with a condensed matter system can alter a material’s properties [1,2], induce new quantum phases of matter [2], and excite coherent lattice excitations [3-5], with the latter providing us with the opportunity to study electron-phonon interaction. The goal of our research program is to deterministically design and produce laser fields capable of executing[ad1] controlled and selective electronic transitions, thereby producing specific non-equilibrium transient states. To this end, we will apply to quantum materials the so-called “coherent control” techniques pioneered in the atomic and molecular field.
The program will include studies of the band structure above the chemical potential in the material of interest using an angle-resolved photoemission spectroscopy (ARPES) in time-of-flight mode (Y. Morita, Tokyo), developing density-functional theory and tight-binding models of the materials, and benchmarking the model with the experimental data (S. Zhdanovich, I. Elfimov[ad2] , UBC). Based on this theoretical characterization of the band structure, an optical field will be designed to create a specific non-equilibrium electronic distribution (D. Manske, MPI and external collaborator J. Sipe, U. of Toronto), to be studied in detailed by time-resolved ARPES (S. Zhdanovich, D.J. Jones, A. Damascelli, UBC). An immediate example of this work could be realization of “k-space optical tweezers” proposed in Ref. 6, with the additional goal of studying relaxation processes induced by electron-phonon and electron-electron scattering[ad3] .
As for the materials to be studied, benchmark and proof of principle experiments will be performed on topological insulators, such as Bi2Se3 and BiSbTe2S. The ultimate goal of this effort will be the study and optical coherent control of electrodynamics and valleytronics related phenomena in the burgeoning class of transition metal dichalcogenides.
[1] D. Werdehausen et al., Science advances 4, 3 (2018).
[2] N.P. Armitage et al., Nature Materials 13, 665 (2014).
[3] E. Papalazarou et al., PRL 108, 256808 (2012).
[4] G. Zengin et al., PRL 114, 157401 (2014).
[5] M.X. Na, A. K. Mills, et al., arXiv:1902.05572 (2019).
[6] P. T. Mahon et al., arXiv:1810.09971 (2018).