Speaker
Description
Many current and future quantum technologies rely on amorphous materials, where translational symmetry is broken, but short-range order with well-defined structural length scales persists (1). This brings forward the fundamental question whether long range order is a necessary condition to establish coherence and structured momentum-dependent electronic state, and how to characterize it in the presence of short-range order.
By using angle resolved photoemission spectroscopy together with our simulations using amorphous Hamiltonians to directly access the electronic states in a momentum resolved manner, we reveal that, even in the absence of long-range order, a well-defined real-space length scale is sufficient to produce dispersive band structures. Moreover, we observe for the first time a repeated Fermi surface structure of duplicated annuli, reminiscent of Brillouin zone-like repetitions.
These results (2), not only lead the way to a new understanding of electronic coherence in solids, but also open the way to the realization of novel momentum-dependent quantum phenomena such as momentum pairing and spin-orbit coupling, in a much broader class of materials than the currently studied ones, lacking long range crystalline translational symmetry.
(1) Quentin Marsal, Dániel Varjas, and Adolfo G. Grushin. PNAS 117 (48) 30260-30265. 2020.
(2) Samuel T. Ciocys, Quentin Marsal et al.. arXiv:2302.05945. 2023.
