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We present a study of a graphene-based Josephson junction with dedicated side gates carved from the same sheet of graphene as the junction itself. These side gates are highly efficient and allow us to modulate carrier density along either edge of the junction in a wide range. In particular, in magnetic fields in the 1- to 2-T range, we are able to populate the next Landau level, resulting in Hall plateaus with conductance that differs from the bulk filling factor. When counter-propagating quantum Hall edge states are introduced along either edge, we observe a supercurrent localized along that edge of the junction. Here, we study these supercurrents as a function of magnetic field and carrier density.
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Transport in strained graphene: Interplay of Abelian and axial magnetic fields
Immersed in external magnetic fields (B), buckled graphene constitutes an ideal tabletop setup, manifesting a confluence of time-reversal symmetry (T) breaking Abelian (B) and T-preserving strain-induced internal axial (b) magnetic fields. In such a system, here we numerically compute two-terminal conductance (G), and four- as well as six-terminal Hall conductivity (σxy) for spinless fermions. On a flat graphene (b=0), the B field produces quantized plateaus at G=±|σxy|=(2n+1)e2/h, where n=0,1,2,⋯. The strain-induced b field lifts the twofold valley degeneracy of higher Landau levels and leads to the formation of additional even-integer plateaus at G=±|σxy|=(2,4,⋯)e2/h, when B>b. While the same sequence of plateaus is observed for G when b>B, the numerical computation of σxy in Hall bar geometries in this regime becomes unstable. A plateau at G=σxy=0 always appears with the onset of a charge-density-wave order, causing a staggered pattern of fermionic density between two sublattices of the honeycomb lattice.
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- Award ID(s):
- 2238679
- PAR ID:
- 10482447
- Publisher / Repository:
- American Physical Society
- Date Published:
- Journal Name:
- Physical Review B
- Volume:
- 108
- Issue:
- 15
- ISSN:
- 2469-9950
- Page Range / eLocation ID:
- 155426
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1103/PhysRevB.108.155426
