Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 7: Fluctuations, Noise, Magnetotransport, and Related Topics
TT 7.11: Vortrag
Montag, 5. September 2022, 17:45–18:00, H23
Bosonization for Q = 0 particle-hole excitations of 2D gapless fermions — •Sebastian Mantilla1 and Inti Sodemann1,2 — 1Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany — 2Institut für Theoretische Physik, Universität Leipzig, 04103 Leipzig, Germany
Understanding the non-perturbative effects of strong interactions on gapless phases of fermions in two-spatial dimensions is one of the major challenges in quantum condensed matter physics. Bosonization in one- and higher-dimensional systems has successfully captured such effects, where the picture of excitations in higher dimensions consists of small deformations of the Fermi surface. We discuss an extension for gapless phases in fermionic systems (e.g., nodal semimetals, Dirac fermions), not describable by the previous formalism since the Fermi surface shrinks to a point and the deformation picture breaks down. The new picture consists of a collection of excitons that considers non-perturbative effects in the weak- and strong-coupling regimes. We apply the formalism in two cases involving interacting electrons in graphene: the corrections to the optical response of 2D free fermions in monolayer graphene, and the weak coupling instability due to electron-hole attractive interactions in bilayer graphene. Our results contribute to understanding the effects of strong interactions in gapless fermions and extend bosonization beyond the picture of Fermi surface deformations.