2,353 research outputs found
Beyond Absolute Immunity: Alternative Protections for Prosecutors Against Ultimate Liability for Section 1983 Suits
Beyond Absolute Immunity: Alternative Protections for Prosecutors Against Ultimate Liability for Section 1983 Suits
Superconductors as ideal spin sources for spintronics
Spin-polarized transport is investigated in normal metal-superconductor (NS)
junctions as a function of interface transmissivity as well as temperature when
the density of states of a superconductor is Zeeman-split in response to an
exchange field (h_exc). Similarly to the "absolute spin-valve effect" predicted
by D. Huertas-Hernando et al. [Phys. Rev. Lett. 88, 047003 (2002)] in
superconducting proximity structures, we show that NS junctions can be used to
generate highly spin-polarized currents, in alternative to half-metallic
ferromagnets. In particular, the spin-polarized current obtained is largely
tunable in magnitude and sign by acting on bias voltage and h_exc. While for
tunnel contacts the current polarization can be as high as 100%, for
transparent junctions it is dominated by the minority spin species. The effect
can be enhanced by electron "cooling" provided by the superconducting gap.Comment: 4 pages, 4 color figures, published versio
Mesoscopic supercurrent transistor controlled by nonequilibrium cooling
The distinctive quasiparticle distribution existing under nonequilibrium in a
superconductor-insulator-normal metal-insulator-superconductor (SINIS)
mesoscopic line is proposed as a novel tool to control the supercurrent
intensity in a long Josephson weak link. We present a description of this
system in the framework of the diffusive-limit quasiclassical Green-function
theory and take into account the effects of inelastic scattering with arbitrary
strength. Supercurrent enhancement and suppression, including a marked
transition to a -junction are striking features leading to a fully tunable
structure. The role of the degree of nonequilibrium, temperature, and materials
choice as well as features like noise, switching time, and current and power
gain are also addressed.Comment: 8 pages, 9 figures, submitted to Journal of Low Temperature Physic
Tailoring Josephson coupling through superconductivity-induced nonequilibrium
The distinctive quasiparticle distribution existing under nonequilibrium in a
superconductor-insulator-normal metal-insulator-superconductor (SINIS)
mesoscopic line is proposed as a novel tool to control the supercurrent
intensity in a long Josephson weak link. We present a description of this
system in the framework of the diffusive-limit quasiclassical Green-function
theory and take into account the effects of inelastic scattering with arbitrary
strength. Supercurrent enhancement and suppression, including a marked
transition to a -junction are striking features leading to a fully tunable
structure.Comment: 4 pages, 4 figure
Local density of states in metal - topological superconductor hybrid systems
We study by means of the recursive Green's function technique the local
density-of-states of (finite and semi-infinite) multi-band spin-orbit coupled
semiconducting nanowires in proximity to an s-wave superconductor and attached
to normal-metal electrodes. When the nanowire is coupled to a normal electrode,
the zero-energy peak, corresponding to the Majorana state in the topological
phase, broadens with increasing transmission between the wire and the leads,
eventually disappearing for ideal interfaces. Interestingly, for a finite
transmission a peak is present also in the normal electrode, even though it has
a smaller amplitude and broadens more rapidly with the strength of the
coupling. Unpaired Majorana states can survive close to a topological phase
transition even when the number of open channels (defined in the absence of
superconductivity) is even. We finally study the Andreev-bound-state spectrum
in superconductor-normal metal-superconductor junctions and find that in
multi-band nanowires the distinction between topologically trivial and
non-trivial systems based on the number of zero-energy crossings is preserved.Comment: 11 pages, 12 figures, published versio
Phase-Dependent Electronic Specific Heat in Mesoscopic Josephson Junctions
We study the influence of superconducting correlations on the electronic
specific heat in a diffusive superconductor-normal metal-superconductor
Josephson junction. We present a description of this system in the framework of
the diffusive-limit Green's function theory, taking into account finite
temperatures, phase difference as well as junction parameters. We find that
proximity effect may lead to a substantial deviation of the specific heat as
compared to that in the normal state, and that it can be largely tuned in
magnitude by changing the phase difference between the superconductors. A
measurement setup to confirm these predictions is also suggested.Comment: 4+ pages, 4 figure
Characterizing electron entanglement in multiterminal mesoscopic conductors
We show that current correlations at the exit ports of a beam splitter can be
used to detect electronic entanglement for a fairly general input state. This
includes the situation where electron pairs can enter the beam splitter from
the same port or be separated due to backscattering. The proposed scheme allows
to discriminate between occupation-number and degree-of-freedom entanglement.Comment: 5 pages, 1 figure. Ref. adde
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