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Identification of superconducting pairing symmetry in twisted bilayer graphene using in-plane magnetic field and strain

TitleIdentification of superconducting pairing symmetry in twisted bilayer graphene using in-plane magnetic field and strain
Publication TypeJournal Article
Year of Publication2019
AuthorsF. Wu, and S. Das Sarma
JournalPhys. Rev. B
Volume99
Pagination220507
Date PublishedJUN 25
Type of ArticleArticle
ISSN2469-9950
Abstract

We show how the pairing symmetry of superconducting states in twisted bilayer graphene can be experimentally identified by theoretically studying effects of externally applied in-plane magnetic field and strain. In the low-field regime, superconducting critical temperature T-c is suppressed by in-plane magnetic field B-parallel to in singlet channels, but is enhanced by weak B-parallel to in triplet channels, providing an important distinction. The in-plane angular dependence of the critical B-parallel to,B-c has a sixfold rotational symmetry, which is broken when strain is present. We show that anisotropy in B-parallel to,B-c generated by strain can be similar for s- and d-wave channels in moire superlattices. The d-wave state is pinned to be nematic by strain and consequently gapless, which is distinguishable from the fully gapped s-wave state by tunneling gap measurements.

DOI10.1103/PhysRevB.99.220507