Theory and simulations on strong pinning of vortex lines by nanoparticles

Abstract

Pinning of vortex lines by array of nanoparticles embedded inside superconductors became the most efficient practical way to achieve high critical currents. In this situation pinning occurs via trapping of the vortex-line segments and the critical current is determined by the typical length of trapped segment. To verify analytical estimates and develop a quantitative description of strong pinning, we numerically simulated isolated vortex lines driven through array of nanoparticles. We found that the critical force grows roughly as a square root of the pin density and it is strongly suppressed by thermal noise. The configurations of pinned lines are strongly anisotropic, displacements in the drive directions are much larger than in the transverse direction. Moreover, we found that the roughening index for the longitudinal displacements exceeds one. This indicates that the local stresses in the critical region increase with the total line length and the elastic description breaks down in the thermodynamic limit. Thermal noise reduces the anisotropy of displacements in the critical regions and straightens the lines.

Upward shift of the vortex solid phase in high-temperature-superconducting wires through high density nanoparticle addition

“…The NPs are responsible for the increases in the wider angular range and the TBs are more effective near the c axis. The broad dome-shape like increase in μ 0 H irr ( θ )– ε ( θ )μ 0 H irr due to the NPs resembles the increases found in J c in samples with nanosized inclusions, both in YBCO and Fe-based superconductors1026272829. The reason for this dome shape (or inverse anisotropy) is found in the fact that while NPs are randomly dispersed, they are not point defects, thus do not follow the electronic mass anisotropy scaling as point defects do21.…”

Strongly enhanced flux pinning in one-step deposition of BaFe2(As0.66P0.33)2 superconductor films with uniformly dispersed BaZrO3 nanoparticles

“…Koshelev et al 39 studied theoretically the effect of an array of nanoparticles on the vortex line pinning and found that the critical current is determined by the length of the trapped segment, leading to L ∝ n . In this model, the critical force grows roughly as n 1/2 .…”

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

“…Several models have been proposed to explain J c (T, H, θ) in cuprate and pnictide superconductors with strong pinning NPs or NRs. 21,24,[50][51][52][53][54][55][56][57][58][59] Although the influence of creep Tuning NP size for enhanced functionality M Miura et al on J c for these superconductors has been known for a long time, 49,60 only a few attempts have been made to link the pinning improvements to J c and S. 60,61 To calculate the temperature, magnetic field and field angle dependence of J c (J c;calc: ), we use J c;calc: T; H; y ð Þ¼ J c0 T; H; y ð Þ1 À Sln t=t 0 ð Þ ð Þ , where t 0 is the effective attempt time, J c0 is the creep-free J c and S is the experimentally obtained flux creep rate.…”