24,248 research outputs found
Linear magnetoresistance on the topological surface
A positive, non-saturating and dominantly linear magnetoresistance is
demonstrated to occur in the surface state of a topological insulator having a
wavevector-linear energy dispersion together with a finite positive Zeeman
energy splitting. This linear magnetoresistance shows up within quite wide
magnetic-field range in a spatially homogenous system of high carrier density
and low mobility in which the conduction electrons are in extended states and
spread over many smeared Landau levels, and is robust against increasing
temperature, in agreement with recent experimental findings in BiSe
nanoribbons.Comment: 7 pages, 4 figure
Elimination of negative differential conductance in an asymmetric molecular transistor by an ac-voltage
We analyze resonant tunneling subject to a non-adiabatic time-dependent
bias-voltage through an asymmetric single molecular quantum dot with coupling
between the electronic and vibrational degrees of freedom using a {\em
Tien-Gordon-type} rate equation. Our results clearly exhibit the appearance of
photon-assisted satellites in the current-voltage characteristics and the
elimination of hot-phonon-induced negative differential conductance with
increasing ac driving amplitude for an asymmetric system. This can be ascribed
to an {\em ac-induced suppression} of unequilibrated (hot) phonons in an
asymmetric system.Comment: Accepted by Appl. Phys. Let
Finite-frequency current (shot) noise in coherent resonant tunneling through a coupled-quantum-dot interferometer
We examine the shot noise spectrum properties of coherent resonant tunneling
in coupled quantum dots in both series and parallel arrangements by means of
quantum rate equations and MacDonald's formula. Our results show that, for a
series-CQD with a relatively high dot-dot hopping ,
( denotes the dot-lead tunnel-coupling
strength), the noise spectrum exhibits a dip at the Rabi frequency, ,
in the case of noninteracting electrons, but the dip is supplanted by a peak in
the case of strong Coulomb repulsion; furthermore, it becomes a dip again for a
completely symmetric parallel-CQD by tuning enclosed magnetic-flux.Comment: 8 pages, 5 figure
Inverse Spin Hall Effect by Spin Injection
Motivated by a recent experiment[Nature {\bf 442}, 176 (2006)], we present a
quantitative microscopic theory to investigate the inverse spin-Hall effect
with spin injection into aluminum considering both intrinsic and extrinsic
spin-orbit couplings using the orthogonalized-plane-wave method. Our
theoretical results are in good agreement with the experimental data. It is
also clear that the magnitude of the anomalous Hall resistivity is mainly due
to contributions from extrinsic skew scattering, while its spatial variation is
determined by the intrinsic spin-orbit coupling.Comment: 5 pages, 3 figure
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