Geometrically Frustrated Coulomb Liquids
by
TDLI Meeting Room 200
We show1 that introducing long-range Coulomb interactions immediately lifts the massive ground state degeneracy induced by geometric frustration for electrons on quarter-filled triangular lattices in the classical limit. Important consequences include the stabilization of a stripe-ordered crystalline (global) ground state, but also the emergence of very many lowlying metastable states with amorphous "stripe-glass" spatial structures2. Melting of the stripe order thus leads to a frustrated Coulomb liquid at intermediate temperatures, showing remarkably slow (viscous) dynamics, with very long relaxation times growing in Arrhenius fashion upon cooling, as typical of strong glass formers. On shorter time scales, the system falls out of equilibrium and displays the aging phenomena characteristic of super-cooled liquids around the glass transition. Our results show remarkable similarity with the recent observations3 of charge-glass behavior in ultra-clean triangular organic materials of the θ- (BEDT-TTF) family. These ideas seem also to be of relevance for very recent discovery5 of self-generated glassiness of polarons in transition-metal dichalcogenide 1T-TaS2.
1. S. Mahmoudian, L. Rademaker, A. Ralko, S. Fratini, and V. Dobrosavljević, Phys. Rev. Lett. 115, 025701.
2. J. Schmalian and P. G. Wolynes, Phys. Rev. Lett. 85, 836 (2000).
3. F. Kagawa, T. Sato, K. Miyagawa, K. Kanoda, Y. Tokura, K. Kobayashi, R. Kumai, and Y. Murakami, Nat. Phys. 9, 422 (2013).
4. N. Ogawa, A. Ueda, H. Mori, M. Kawasaki, and Y. Tokura, Phys. Rev. B 91, 041101 (2015).
5. Y. Gerasimenko, I. Vaskivskyi, J. Ravnik, Jaka Vodeb, V. V. Kabanov, and D. Mihailovic, preprint, arXiv:1803.00255.
Figure 1: (a) Structure factor C(k) of the frustrated Coulomb liquid obtained for a L = 36 triangular lattice size and averaged over 1000 independent equilibrated Monte Carlo runs at T = 0.04V above the melting transition. Clearly defined dffuse Bragg peaks are observed at the (linear) stripe order M-point, and symmetry equivalent points. (b) Same, plotted along the high-symmetry lines of the Brillouin zone drawn in panel (a); (c) A snapshot illustrating a typical “stripe liquid" configuration.
Prof. Dobrosavljevic obtained his B.Sc. at the University of Belgrade in 1983, after which he moved to the US, where he earned his M.Sc. (1985) and his Ph.D. ta Brown University (1988). He carried postdoctoral research at the University of Maryland (1989-1991) and Rutgers University (1991-1995). He joined the Faculty at the Department of Physics at Florida State University (FSU), where he is currently a Professor of Physics, since 2006. He is also serving as the Director of the Condensed Matter Sciences – Theory program at the National High Magnetic Field Laboratory at FSU (2006-present). Prof. Dobrosavljevic is an expert in theories of strongly correlated electronic systems with and without disorder, and is primarily interested in understanding the fundamental nature of the Metal-Insulator Quantum Phase Transition.
