Metastable states of a flux-line lattice studied by transport and small-angle neutron scattering

Abstract

Flux-line lattice ͑FLL͒ states have been studied using transport measurements and small-angle neutron scattering in low-T c materials. In Pb-In, the bulk dislocations in the FLL do not influence the transport properties. In Fe-doped NbSe 2 , transport properties can differ after a field cooling ͑FC͒ or a zero field cooling ͑ZFC͒ procedure, as previously reported. The ZFC FLL is found ordered with narrow Bragg peaks and is linked to a linear V͑I͒ curve and to a superficial critical current. The FC FLL pattern exhibits two Bragg peaks and the corresponding V͑I͒ curve shows an S-shape. This can be explained by the coexistence of two ordered FLLs slightly tilted from the applied field direction by different superficial currents. These currents are wiped out when the transport current is increased.

Persistence of an ordered flux line lattice above the second peak inBi2Sr2CaCu2O8Pautrat1, Simon2, Goupil3 et al. 2007Phys. Rev. BSelf Cite150170View full textAdd to dashboardCite

“…A peculiar distribution of surface currents has been proposed. 25 Transport experiments suggest that these latter surface currents can be also important in Bi-2212, and metastable transport properties, very similar properties with those observed in NbSe 2 , are also observed. 26 It is very important to note that if there is a coexistence between two states, the states observed here under the strongest magnetic fields can be metastable.…”

“…In this latter case, the FLL state at low field has been clearly identified as a conventional FLL ͑or a Bragg glass͒. 25 The structure of the high-field state is less clear. A disordered state has not been confirmed by experiments measuring the FLL order.…”

Narrow-band noise due to the moving vortex lattice in superconducting niobium

“…Note neutron-scattering experiments in conventional low-T c materials indicate also that the VL is much more regular than expected for a model of independent flux bundles motion at the beginning of its motion. 7,26,27 …”

“…At higher current, in the flux-flow regime, the vortices tend to form a long-range ordered state, as experimentally confirmed by the existence of orientational and positional long-range order from neutron-scattering experiments. 7 The exact nature of the ordered state has been largely debated. Theories predict a crystalline 2 or a smectic order, 4 what refer closely to elastically coupled or decoupled channels in a moving glass.…”

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

“…[11], where the voltage noise was attributed to the dynamical annealing of a disordered vortex phase nucleated close to the edges. We stress that this latter interpretation was proposed for the peculiar case of the peak effect in N bSe 2 , where two macroscopic critical current states coexist in the sample ( [12,13] and references herein), and where the large noise values are coming from the kinetic between these two states. This was shown to correspond to non-Gaussian noise by a second spectrum analysis [14].…”