Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Date
2021-07-22
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en
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10
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Physical Review X, Volume 11, issue 3
Abstract
Electrons with large kinetic energy have a superconducting instability for infinitesimal attractive interactions. Quenching the kinetic energy and creating a flat band renders an infinitesimal repulsive interaction the relevant perturbation. Thus, flat-band systems are an ideal platform to study the competition of superconductivity and magnetism and their possible coexistence. Recent advances in the field of twisted bilayer graphene highlight this in the context of two-dimensional materials. Two dimensions, however, put severe restrictions on the stability of the low-temperature phases due to enhanced fluctuations. Only three-dimensional flat bands can solve the conundrum of combining the exotic flat-band phases with stable order existing at high temperatures. Here, we present a way to generate such flat bands through strain engineering in topological nodal-line semimetals. We present analytical and numerical evidence for this scenario and study the competition of the arising superconducting and magnetic orders as a function of externally controlled parameters. We show that the order parameter is rigid because the three-dimensional quantum geometry of the Bloch wave functions leads to a large superfluid stiffness in all three directions. Using density-functional theory and numerical tight-binding calculations, we further apply our theory to strained rhombohedral graphite and CaAgP materials.Description
Funding Information: Fundacja na rzecz Nauki Polskiej European Commission Uniwersytet Warszawski Funding Information: We thank Raquel Queiroz, Leslie Schoop, Roni Ilan, and Adolfo Grushin for useful discussions. This work was supported by the Foundation for Polish Science through the International Research Agendas program co-financed by the European Union within the Smart Growth Operational Programme. We acknowledge access to the computing facilities of the Interdisciplinary Center of Modeling at the University of Warsaw, Grants No. G73-23, No. G75-10, and No. G84-4. Publisher Copyright: © 2021 Published by the American Physical Society
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Lau, A, Hyart, T, Autieri, C, Chen, A & Pikulin, D I 2021, ' Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals ', Physical Review X, vol. 11, no. 3, 031017 . https://doi.org/10.1103/PhysRevX.11.031017