1,281 research outputs found
Flux domes in superconducting films without edges
Domelike magnetic-flux-density distributions previously have been observed
experimentally and analyzed theoretically in superconducting films with edges,
such as in strips and thin plates. Such flux domes have been explained as
arising from a combination of strong geometric barriers and weak bulk pinning.
In this paper we predict that, even in films with bulk pinning, flux domes also
occur when vortices and antivortices are produced far from the film edges
underneath current-carrying wires, coils, or permanent magnets placed above the
film. Vortex-antivortex pairs penetrating through the film are generated when
the magnetic field parallel to the surface exceeds H_{c1}+K_c, where H_{c1} is
the lower critical field and K_c = j_c d is the critical sheet-current density
(the product of the bulk critical current density j_c and the film thickness
d). The vortices and antivortices move in opposite directions to locations
where they join others to create separated vortex and antivortex flux domes. We
consider a simple arrangement of a pair of current-carrying wires carrying
current I_0 in opposite directions and calculate the magnetic-field and
current-density distributions as a function of I_0 both in the
bulk-pinning-free case (K_c = 0) and in the presence of bulk pinning,
characterized by a field-independent critical sheet-current density (K_c > 0).Comment: 15 pages, 23 figure
Damped Topological Magnons in the Kagom\'{e}-Lattice Ferromagnets
We demonstrate that interactions can substantially undermine the
free-particle description of magnons in ferromagnets on geometrically
frustrated lattices. The anharmonic coupling, facilitated by the
Dzyaloshinskii-Moriya interaction, and a highly-degenerate two-magnon continuum
yield a strong, non-perturbative damping of the high-energy magnon modes. We
provide a detailed account of the effect for the ferromagnet on the
kagom\'e lattice and propose further experiments.Comment: 4.5 p + 4 figs main, 8 p + 16 figs supplemental, typos correcte
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