3,329 research outputs found
Anisotropic minimal conductivity of graphene bilayers
Fermi line of bilayer graphene at zero energy is transformed into four
separated points positioned trigonally at the corner of the hexagonal first
Brillouin zone. We show that as a result of this trigonal splitting the minimal
conductivity of an undoped bilayer graphene strip becomes anisotropic with
respect to the orientation of the connected electrodes and finds a
dependence on its length on the characteristic scale determined by the inverse of k-space distance of two Dirac
points. The minimum conductivity increases from a universal isotropic value
for a short strip to a higher
anisotropic value for longer strips, which in the limit of varies
from at to over an
angle range .Comment: 4 pages, 2 figure
Gate-controlled supercurrent reversal in MoS-based Josephson junctions
Motivated by recent experiments revealing superconductivity in MoS, we
investigate the Josephson effect in the monolayer MoS at the presence of an
exchange splitting. We show that the supercurrent reversal known as
transition can occur by varying the doping via gate voltages. This is in
contrast to common superconductor/ferromagnet/superconductor junctions in which
successive transition take place with the variation of junction length
or temperature. In fact for the case of MoS we find that both the amplitude
and the period of oscillations show a dependence on the doping which explains
the predicted doping induced supercurrent reversal. These effects comes from
the dependence of density and Fermi velocity on the doping strength beside the
intrinsic spin splitting in the valence band which originates from spin-orbit
interaction.Comment: 5 pages, 3 figure
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