Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals

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...

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Autores principales:	Alexander Lau, Timo Hyart, Carmine Autieri, Anffany Chen, Dmitry I. Pikulin
Formato:	article
Lenguaje:	EN
Publicado:	American Physical Society 2021
Materias:	Physics QC1-999
Acceso en línea:	https://doaj.org/article/5f4e3839bb4b40ddb91d13fa049040fc
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spelling	oai:doaj.org-article:5f4e3839bb4b40ddb91d13fa049040fc2021-12-02T17:03:30ZDesigning Three-Dimensional Flat Bands in Nodal-Line Semimetals10.1103/PhysRevX.11.0310172160-3308https://doaj.org/article/5f4e3839bb4b40ddb91d13fa049040fc2021-07-01T00:00:00Zhttp://doi.org/10.1103/PhysRevX.11.031017http://doi.org/10.1103/PhysRevX.11.031017https://doaj.org/toc/2160-3308Electrons 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.Alexander LauTimo HyartCarmine AutieriAnffany ChenDmitry I. PikulinAmerican Physical SocietyarticlePhysicsQC1-999ENPhysical Review X, Vol 11, Iss 3, p 031017 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Physics QC1-999
spellingShingle	Physics QC1-999 Alexander Lau Timo Hyart Carmine Autieri Anffany Chen Dmitry I. Pikulin Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
description	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.
format	article
author	Alexander Lau Timo Hyart Carmine Autieri Anffany Chen Dmitry I. Pikulin
author_facet	Alexander Lau Timo Hyart Carmine Autieri Anffany Chen Dmitry I. Pikulin
author_sort	Alexander Lau
title	Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
title_short	Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
title_full	Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
title_fullStr	Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
title_full_unstemmed	Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals
title_sort	designing three-dimensional flat bands in nodal-line semimetals
publisher	American Physical Society
publishDate	2021
url	https://doaj.org/article/5f4e3839bb4b40ddb91d13fa049040fc
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Designing Three-Dimensional Flat Bands in Nodal-Line Semimetals

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