5 research outputs found
Kinetic investigation on extrinsic spin Hall effect induced by skew scattering
The kinetics of the extrinsic spin Hall conductivity induced by the skew
scattering is performed from the fully microscopic kinetic spin Bloch equation
approach in GaAs symmetric quantum well. In the steady state, the
extrinsic spin Hall current/conductivity vanishes for the linear-
dependent spin-orbit coupling and is very small for the cubic-
dependent spin-orbit coupling. The spin precession induced by the
Dresselhaus/Rashba spin-orbit coupling plays a very important role in the
vanishment of the extrinsic spin Hall conductivity in the steady state. An
in-plane spin polarization is induced by the skew scattering, with the help of
the spin-orbit coupling. This spin polarization is very different from the
current-induced spin polarization.Comment: 5 pages, 2 figures, to be published in JPC
Photocurrent imaging and efficient photon detection in a graphene transistor
We measure the channel potential of a graphene transistor using a scanning
photocurrent imaging technique. We show that at a certain gate bias, the impact
of the metal on the channel potential profile extends into the channel for more
than 1/3 of the total channel length from both source and drain sides, hence
most of the channel is affected by the metal. The potential barrier between the
metal controlled graphene and bulk graphene channel is also measured at various
gate biases. As the gate bias exceeds the Dirac point voltage, VDirac, the
original p-type graphene channel turns into a p-n-p channel. When light is
focused on the p-n junctions, an impressive external responsivity of 0.001 A/W
is achieved, given that only a single layer of atoms are involved in photon
detection.Comment: 24 pages, 4 figure