14,465 research outputs found
Vortex Softening: Origin of the second peak effect in BiSrCaCuO
Transverse ac permeability measurements in BiSrCaCuO single crystals at low fields and temperatures in a vortex configuration
free of external forces show that the decrease of the critical current as
measured by magnetization loops at the second peak effect is an artifact due to
creep. On the other hand, the increase of critical current at the second peak
is due to a genuine softening of the tilting elastic properties of vortices in
the individual pinning regime that precedes the transition to a disorder state.Comment: 4 pages, 5 figures, RevTex, two column versio
Towards a new quantization of Dirac's monopole
There are several mathematical and physical reasons why Dirac's quantization
must hold. How far one can go without it remains an open problem. The present
work outlines a few steps in this direction.Comment: To appear in Proceedings of "IV Taller de la Division de Gravitacion
y Fisica Matematica". Misprints corrected, references and acknowledgments
adde
Critical current and topology of the supercooled vortex state in NbSe2
We study the behavior of the critical current, Ic(H,T), of pure and Fe doped
NbSe2 crystals in the denominated disordered vortex region, limited by the
critical field Hc2(T) and the field Hp(T) at which the peak effect in Ic(H,T)
is detected. The critical current follows an individual pinning response as
demonstrated by its field independent universal function of the superfluid
density. Transport measurements combined with Bitter decorations show no
evidence of the existence of an amorphous phase in the high temperature region.Comment: 7 pages, figures included. Submitted to Phys. Rev.
On representations of the rotation group and magnetic monopoles
Recently (Phys. Lett. A302 (2002) 253, hep-th/0208210; hep-th/0403146)
employing bounded infinite-dimensional representations of the rotation group we
have argued that one can obtain the consistent monopole theory with generalized
Dirac quantization condition, , where is the
weight of the Dirac string. Here we extend this proof to the unbounded
infinite-dimensional representations.Comment: References adde
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