1,764 research outputs found
Discrete Dirac system: rectangular Weyl functions, direct and inverse problems
A transfer matrix function representation of the fundamental solution of the
general-type discrete Dirac system, corresponding to rectangular Schur
coefficients and Weyl functions, is obtained. Connections with Szeg\"o
recurrence, Schur coefficients and structured matrices are treated.
Borg-Marchenko-type uniqueness theorem is derived. Inverse problems on the
interval and semiaxis are solved.Comment: Section 2 is improved in the second version: some new results on
Halmos extension are added and arguments are simplifie
Reverse-domain superconductivity in superconductor-ferromagnet hybrids: effect of a vortex-free channel on the symmetry of I-V characteristics
We demonstrate experimentally that the presence of a single domain wall in an
underlying ferromagnetic BaFe_{12}O_{19} substrate can induce a considerable
asymmetry in the current (I) - voltage (V) characteristics of a superconducting
Al bridge. The observed diode-like effect, i.e. polarity-dependent critical
current, is associated with the formation of a vortex-free channel inside the
superconducting area which increases the total current flowing through the
superconducting bridge without dissipation. The vortex-free region appears only
for a certain sign of the injected current and for a limited range of the
external magnetic field
Classical analogy for the deflection of flux avalanches by a metallic layer
Sudden avalanches of magnetic flux bursting into a superconducting sample
undergo deflections of their trajectories when encountering a conductive layer
deposited on top of the superconductor. Remarkably, in some cases flux is
totally excluded from the area covered by the conductive layer. We present a
simple classical model that accounts for this behaviour and considers a
magnetic monopole approaching a semi-infinite conductive plane. This model
suggests that magnetic braking is an important mechanism responsible for
avalanche deflection.Comment: 14 pages, 5 figure
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