Monday, October 10, 2022 from 2:30-3:30 p.m.
Location: 325 Physics South Hall & Zoom
Speaker: Alex Thomson, University of California, Davis
Abstract: Since the detection of superconductivity in magic angle twisted bilayer graphene (MATBG), superconducting phases have been observed in a variety of graphene heterostructure systems. Surprisingly, under the right conditions, even Bernal bilayer graphene (BBG)—the most stable bilayer configuration—displays not only superconductivity but also the ‘cascade’ of polarized states as a function of doping familiar from MATBG. In this talk, I will discuss the recent experimental discovery that placing WSe2 next to BBG encourages Cooper pairing to an extraordinary degree: while BBG encapsulated in hexagonal boron nitride does not admit superconductivity except in the presence of an in-plane magnetic field, superconductivity in BBG/WSe2 heterostructures appears over a much broader density window with a tenfold enhanced maximal Tc. This promotion of superconductivity by WSe2 is reminiscent of the superconducting phases seen in WSe2-proximitized twisted bilayer graphene far from the magic angle, suggesting that the mechanism underlying superconductivity in BBG may have much in common with the physics at play in moiré graphene systems and vice versa. I argue that WSe2-induced spin-orbit coupling selects a ground state amenable to superconductivity and use the in-plane magnetic field dependence of the system to identify the intervalley coherent phase as a likely parent to the superconductor.
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