Hyperbolic enhancement of photocurrent patterns in minimally twisted bilayer graphene

Abstract

Quasi-periodic moiré patterns and their effect on electronic properties of twisted bilayer graphene (TBG) have been intensely studied. At small twist angle $\theta$, due to atomic reconstruction, the moiré superlattice morphs into a network of narrow domain walls separating micron-scale AB and BA stacking regions. We use scanning probe photocurrent imaging to resolve nanoscale variations of the Seebeck coefficient occurring at these domain walls. The observed features become enhanced in a range of mid-infrared frequencies where the hexagonal boron nitride (hBN), which we use as a TBG substrate, is optically hyperbolic. Our results illustrate new capabilities of nano-photocurrent technique for probing nanoscale electronic inhomogeneities in two-dimensional materials.

References in corpus (10)

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• The electronic properties of bilayer graphene
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• Subdiffractional focusing and guiding of polaritonic rays in a natural hyperbolic material
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• Electrical detection of hyperbolic phonon-polaritons in heterostructures of graphene and boron nitride

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• Nano-imaging photoresponse in a moiré unit cell
• Perspective: Phonon polaritons for infrared optoelectronics
• Visualizing moiré ferroelectricity via plasmons and nano-photocurrent in graphene/twisted-WSe2 structures
• Charge density wave and finite-temperature transport in minimally twisted bilayer graphene
• Theory of plasmonic edge states in chiral bilayer systems
• Nonlinear intensity dependence of photogalvanics and photoconductance induced by terahertz laser radiation in twisted bilayer graphene close to magic angle
• Nonlinear optical responses and quantum geometry in rhombohedral trilayer graphene
• Infrared photoresistance as a sensitive probe of electronic transport in twisted bilayer graphene
• Intrinsic and extrinsic photogalvanic effects in twisted bilayer graphene
• Gradient polaritonic surface with space-variant switchable light-matter interactions in 2D moire superlattices
• Electrically driven plasmon-polaritonic bistability in Dirac electron tunneling transistors
• Local optical conductivity of strain solitons in bilayer graphene with arbitrary soliton angle