Nematicity Arising from a Chiral Superconducting Ground State in Magic-Angle Twisted Bilayer Graphene under In-Plane Magnetic Fields

Abstract

Recent measurements of the resistivity in magic-angle twisted bilayer graphene near the superconducting transition temperature show two-fold anisotropy, or nematicity, when changing the direction of an in-plane magnetic field [Cao \textit{et al.}, Science \textbf{372}, 264 (2021)]. This was interpreted as strong evidence for exotic nematic superconductivity instead of the widely proposed chiral superconductivity. Counter-intuitively, we demonstrate that in two-dimensional chiral superconductors the in-plane magnetic field can hybridize the two chiral superconducting order parameters to induce a phase that shows nematicity in the transport response. Its paraconductivity is modulated as $\cos (2{\theta }_{\mathbf{B}})$, with ${\theta }_{\mathbf{B}}$ being the direction of the in-plane magnetic field, consistent with experiment in twisted bilayer graphene. We therefore suggest that the nematic response reported by Cao \textit{et al.} does not rule out a chiral superconducting ground state.

6 pages, 2 figures

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Cited by in corpus (2)

• Light-matter coupling and quantum geometry in moiré materials
• Electric-field-tunable electronic nematic order in twisted double-bilayer graphene