Universität zu Köln

Classen, Laura, Honerkamp, Carsten and Scherer, Michael M. ORCID: 0000-0003-0766-9949 (2019). Competing phases of interacting electrons on triangular lattices in moire heterostructures. Phys. Rev. B, 99 (19). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2469-9969

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Abstract

We study the quantum many-body instabilities of interacting electrons with SU(2) x SU(2) symmetry in spin and orbital degrees of freedom on the triangular lattice near van-Hove filling. Our work is motivated by effective models for the flat bands in hexagonal moire heterostructures like twisted bilayer boron nitride and trilayer graphene-boron nitride systems. We consider an extended Hubbard model including onsite Hubbard and Hund's couplings, as well as nearest-neighbor exchange interactions, and analyze the different ordering tendencies with the help of an unbiased functional renormalization group approach. We find three classes of instabilities controlled by the filling and bare interactions. For a nested Fermi surface at van-Hove filling, Hund-like couplings induce a weak instability towards spin or orbital density wave phases. An SU(4) exchange interaction moves the system towards a Chern insulator, which is robust with respect to perturbations from Hund-like interactions or deviations from perfect nesting. Further, in an extended range of fillings and interactions, we find topological d +/- id and (spin-singlet)-(orbital-singlet) f-wave superconductivity.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Classen, Laura UNSPECIFIED UNSPECIFIED UNSPECIFIED Honerkamp, Carsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Scherer, Michael M. UNSPECIFIED orcid.org/0000-0003-0766-9949 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-148335
DOI:	10.1103/PhysRevB.99.195120
Journal or Publication Title:	Phys. Rev. B
Volume:	99
Number:	19
Date:	2019
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2469-9969
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FUNCTIONAL RENORMALIZATION-GROUP; GRAPHENE; SUPERCONDUCTIVITY; REALIZATION; INSULATOR; MODEL Multiple languages Materials Science, Multidisciplinary; Physics, Applied; Physics, Condensed Matter Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14833