Controlling flux flow dissipation by changing flux pinning in superconducting films

Abstract

We study the flux flow state in superconducting materials characterized by rather strong intrinsic pinning, such as Nb, NbN, and nanostructured Al thin films, in which we drag the superconducting dissipative state into the normal state by current biasing. We modify the vortex pinning strength either by ion irradiation, by tuning the measuring temperature or by including artificial pinning centers. We measure critical flux flow voltages for all materials and the same effect is observed: switching to low flux flow dissipations at low fields for an intermediate pinning regime. This mechanism offers a way to additionally promote the stability of the superconducting state. VC 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4718309

Angular dependence of vortex instability in a layered superconductor: the case study of Fe(Se,Te) material

“…This is indeed another case in which the instability voltage V *( θ , H , T ) and the instability current I *( θ , H , T ) are affected by the pinning mechanism 36,42,43 . However, I * turns to be more robust and isotropic in IBS rather than in HTS, thus promoting this material as an high-field superconductor.…”

“…Although we are used to correlate flux pinning with critical current, and flux motion with dissipation, by gradually increasing the bias current above I c the vortex motion can reach a speed limit which is unavoidably affected by pinning mechanism itself 35 . Either due to material defects 4,36 , or to geometrical barrier 37,38 , pinning becomes crucial in flux flow motion at high velocities too. Can the intrinsic layered structure of this Fe(Se,Te) superconductor make feel its influence?…”

Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films

“…This prediction has been indeed observed in many different superconducting materials, [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] thus demonstrating the universal character of this phenomenon. According to the LO model, the current density J * and the voltage V * at the point where the instability is triggered, are uniquely defined.…”

“…Later refinements of the LO model have permitted to explain the widely observed low field dependent v c ∼ 1/ √ B in low pinning samples 4 and the switching to an opposity tendency v c ∼ H when pinning plays an important role. 14,19,20 A point that remains unclear in the LO formulation is to what exactly corresponds the more dissipative dynamic state after the instability has been triggered. This issue has been partially addressed by Vodolazov and Peeters 21 using time-dependent Ginzburg-Landau theory in a pinning-free wide superconducting stripe.…”

Mapping degenerate vortex states in a kagome lattice of elongated antidots via scanning Hall probe microscopy

“…The appeal and advantage of superconducting systems is that the size and number of the particles can be tuned by changing the temperature and the magnetic field, respectively. In addition, the flexibility in the design and fabrication of artificial vortex traps in superconducting films has stimulated, during the past decade, an in-depth investigation of the interplay between pinning landscape and vortex pattern symmetry [16], influence of the pinning center's size and period [17][18][19][20], vortex rectification on a kagome-like array [21], competition between ordered and disordered defects [22][23][24], or pinning energy dispersion [25,26], to name a few.…”