Magnetic Field Concentrator Based on the Superconducting Films with Nanosize Cuts

Optimal active strip nanostructuring of a magnetic field concentrator based on superconducting films allows to further increase the concentration ratio of the device. The magnetically sensitive element was placed between two concentrator rings lying in the same plane without crossing. Calculated concentration coefficients F and F ₀ of a planar concentrator with an active strip with nanosize cuts and without them. Different position of the cuts in the active strip of the concentrator were invastigated, as well as different values of the magnetically sensitive element width w ₀ and the London penetration depth λ. In the calculations it was assumed that the width of the cut w _p coincides with the distance w _a between the ends of the near concentrator and magnetically sensitive element. The active strip width w _s and width of the superconducting branch were multiples of w _a . It turned out that as w ₀ decreases, F ₀ increases and F decreases but the total concentration coefficient F* = F ₀ F increases. F* value for a concentrator based on the niobium film (λ ∼ 50nm ) is higher than for the concentrator based on films Y-123 or Bi-2223 (λ ≥ 250nm). The considered concentrator with nanosize cuts will increase the efficiency of combined magnetic field sensors, SQUIDs, and other sensors with a resolution of ≤ 1 pT. (paper)