Combined Magnetic Field Sensor with Nanosized Elements

Abstract

We investigate a superconducting film ring with a narrowed part (active strip ) used as a magnetic field concentrator or magnetic flux transformer in combined magnetic field sensors. Fragmentation (nanostructuring) of the active strip in numerous branches and cuts and simulation of their nanoscale size and positions make it possible to significantly enhance the efficiency of the combined magnetic field sensor with a resolution of ≤10 pT, which operates on the base of superconductivity and spintronics phenomena. It was established that the efficiency of concentration of a measured magnetic field on a magnetosensitive element based on the giant magnetoresistive effect can be enhanced using fragmentation of an active strip by cuts with a width of 20−350 nm. The magnetic field concentrator with low-temperature superconductor (e.g., niobium with the London penetration depth $\lambda \sim 60 \, {\text{nm}}$) films exhibits higher efficiency, than the concentrator with high-temperature superconductor films of the Y-123 or Bi-2223 systems with $\lambda \sim 2 5 0\,{\text{nm}}$. The magnetic field resolution and maximum field values estimated for a combined magnetic field sensor based on different low- and high-temperature layers and spintronic elements are ≤1 fT and ≤40 µT (the Earth’s magnetic field), respectively. Characteristics of the investigated sensor are comparable with the parameters of SQUIDs .