Junctions and Superconducting Symmetry in Twisted Bilayer Graphene

Héctor Sainz-Cruz; Pierre A. Pantaleón; Võ Tiến Phong; Alejandro Jimeno-Pozo; Francisco Guinea

doi:10.1103/PhysRevLett.131.016003

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Junctions and Superconducting Symmetry in Twisted Bilayer Graphene

Héctor Sainz-Cruz, Pierre A. Pantaleón, Võ Tiến Phong, Alejandro Jimeno-Pozo, Francisco Guinea

DOI 10.1103/PhysRevLett.131.016003 · Physical Review Letters

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Abstract

Junctions provide a wealth of information on the symmetry of the order parameter of superconductors. We analyze junctions between a scanning tunneling microscope (STM) tip and superconducting twisted bilayer graphene (TBG) and TBG Josephson junctions (JJs). We compare superconducting phases that are even or odd under valley exchange (s- or f-wave). The critical current in mixed (s and f) JJs strongly depends on the angle between the junction and the lattice. In STM-TBG junctions, due to Andreev reflection, the f-wave leads to a prominent peak in subgap conductance, as seen in experiments.