5,075 research outputs found
Crossed Andreev reflection at spin-active interfaces
With the aid of the quasiclassical Eilenberger formalism we develop a theory
of non-local electron transport across three-terminal ballistic
normal-superconducting-normal (NSN) devices with spin-active NS interfaces. The
phenomenon of crossed Andreev reflection (CAR) is known to play the key role in
such transport. We demonstrate that CAR is highly sensitive to electron spins
and yields a rich variety of properties of non-local conductance which we
describe non-perturbatively at arbitrary voltages, temperature, spin-dependent
interface transmissions and their polarizations. Our results can be applied to
multi-terminal hybrid structures with normal, ferromagnetic and half-metallic
electrodes and can be directly tested in future experiments.Comment: 11 pages, 7 figures; figures 6 and 7 are corrected; version published
in Phys. Rev.
NN potentials from inverse scattering in the J-matrix approach
An approximate inverse scattering method [7,8] has been used to construct
separable potentials with the Laguerre form factors. As an application, we
invert the phase shifts of proton-proton in the and
channels and neutron-proton in the channel elastic scattering. In
the latter case the deuteron wave function of a realistic potential was
used as input.Comment: LaTex2e, 17 pages, 3 Postscript figures; corrected typo
Nonlocal Andreev reflection at high transmissions
We analyze non-local effects in electron transport across three-terminal
normal-superconducting-normal (NSN) structures. Subgap electrons entering
S-electrode from one N-metal may form Cooper pairs with their counterparts
penetrating from another N-metal. This phenomenon of crossed Andreev reflection
-- combined with normal scattering at SN interfaces -- yields two different
contributions to non-local conductance which we evaluate non-perturbatively at
arbitrary interface transmissions. Both these contributions reach their maximum
values at fully transmitting interfaces and demonstrate interesting features
which can be tested in future experiments.Comment: 4 pages, 4 figure
Depinning transition of dislocation assemblies: pileup and low-angle grain boundary
We investigate the depinning transition occurring in dislocation assemblies.
In particular, we consider the cases of regularly spaced pileups and low angle
grain boundaries interacting with a disordered stress landscape provided by
solute atoms, or by other immobile dislocations present in non-active slip
systems. Using linear elasticity, we compute the stress originated by small
deformations of these assemblies and the corresponding energy cost in two and
three dimensions. Contrary to the case of isolated dislocation lines, which are
usually approximated as elastic strings with an effective line tension, the
deformations of a dislocation assembly cannot be described by local elastic
interactions with a constant tension or stiffness. A nonlocal elastic kernel
results as a consequence of long range interactions between dislocations. In
light of this result, we revise statistical depinning theories and find novel
results for Zener pinning in grain growth. Finally, we discuss the scaling
properties of the dynamics of dislocation assemblies and compare theoretical
results with numerical simulations.Comment: 13 pages, 8 figure
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