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

Abstract

We report on critical currents and voltage noise measurements in Niobium strips in the superconducting state, in the presence of a bulk vortex lattice ($B<B_{C2}$) and in the surface superconducting state ($B_{c2}<B<B_{C3}$). For homogeneous surfaces, the correlation length of the current fluctuations can be associated with the electromagnetic skin depth of vortex superficial instabilities. The modification of the surface state by means of low energy irradiation induces a strong modification of the critical current and of the noise. The appearance of a corner frequency in the spectral domain can be linked with the low wave-vectors of the artificial corrugation. Since this latter occurs only for $B<B_{C2}$, we propose that the long-range interactions allow the correlation length to extend up to values imposed by the surface topography.

accepted for publication in PRB

References in corpus (6)

• The Flux-Line Lattice in Superconductors
• Instabilities and disorder-driven first-order transition of the vortex lattice
• Quantitative analysis of the critical current due to vortex pinning by surface corrugation
• Metastable states of a flux line lattice studied by transport and Small Angle Neutron Scattering
• Voltage noise and surface current fluctuations in the superconducting surface sheath
• Longitudinal and transverse noise in a moving Vortex Lattice

Cited by in corpus (5)

• The effect of collective spin-1 excitations on electronic spectra in high-Tc superconductors
• Change of surface critical current in the surface superconductivity and mixed states of superconducting Niobium
• A study of flux lines lattice order and critical current with time of flight small angle neutron scattering
• Narrow-band noise due to the moving vortex lattice in superconducting niobium
• New Insight into the Fluctuations of the Moving Vortex Lattice: Non-Gaussian Noise and Levy Flights