9 research outputs found
Mesoscopic cross-film cryotrons: Vortex trapping and dc-Josephson-like oscillations of the critical current
We investigate theoretically and experimentally the transport properties of a
plain Al superconducting strip in the presence of a single straight
current-carrying wire, oriented perpendicular to the superconducting strip. It
is well known that the critical current of the superconducting strip, Ic, in
such cryotron--like system can be tuned by changing the current in the control
wire, Iw. We demonstrated that the discrete change in the number of the pinned
vortices/antivortices inside the narrow and long strip nearby the
current-carrying wire results in a peculiar oscillatory dependence of Ic on Iw.Comment: 8 pages, 8 figure
Whispering Vortices
Experiments indicating the excitation of whispering gallery type
electromagnetic modes by a vortex moving in an annular Josephson junction are
reported. At relativistic velocities the Josephson vortex interacts with the
modes of the superconducting stripline resonator giving rise to novel
resonances on the current-voltage characteristic of the junction. The
experimental data are in good agreement with analysis and numerical
calculations based on the two-dimensional sine--Gordon model.Comment: 5 pages, 5 figures, text shortened to fit 4 pages, correction of
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Magnetization curves for two-dimensional rectangular lattices of permalloy nanoparticles: experimental investigation and numerical simulation
Abstract This work is concerned with the behaviour of a regular 2D rectangular lattice of Ni 3 Fe nanoparticles, determined by the dipole interaction between them. The samples under study, prepared by electron-beam lithography, consisted of about 10 5 particles approximately 50 nm in size. The magnetization curves were studied by Hall magnetometry for different external magnetic field orientations at 4.2 K and 77 K. The results indicate a collective behaviour of the system. The magnetization curves depend on the external magnetic field direction and temperature; the system exhibits multistability. A model system of interacting 3D magnetic dipoles forming a rectangular lattice was numerically simulated by solving a system of stochastic Landau-Lifshitz equations. The multistability of the system and steps in the magnetization curves were obtained. It is shown analytically that the shape of the magnetization curves depends on the character of the interaction in the system