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| VOLUME 102 (2015) | ISSUE 12 | PAGE 943 |
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Fate of the Wiedemann-Franz law near quantum critical points of electron systems in solids
V. A. Khodel+*, J. W. Clark*×, V. R. Shaginyan°, M. V. Zverev+∇
+National Research Centre "Kurchatov Institute", 123182 Moscow, Russia *McDonnell Center for the Space Science and Department of Physics, Washington University, MO 63130 St. Louis, USA ×Centro de Ci  ncias Matemáticas, Universidade de Madeira, 9000-390 Funchal, Madeira, Portugal°Petersburg Nuclear Physics Institute, NRC Kurchatov Institute, 188300 Gatchina, Russia ∇Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
Abstract
We introduce and analyze two different scenarios for violation of the Wiedemann-Franz law in strongly correlated electron systems of solids, close to a topological quantum critical point (TQCP) where the density of states N(0) diverges. The first, applicable to the Fermi-liquid (FL) side of the TQCP, involves a transverse zero-sound collective mode that opens a new channel for the thermal conductivity, thereby enhancing the Lorenz number L(0) relative to the value L0=π2k2B/3e2 dictated by conventional FL theory. The second mechanism for violation of the WF law, relevant to the non-Fermi-liquid (NFL) side of the TQCP, involves the formation of a flat band and leads instead to a reduction of the Lorenz number. |