Effects of magnetic field on two-dimensional Superconducting Quantum   Interference Filters
  We present an experimental study of two-dimensional superconducting quantum interference filters (2D-SQIFs) in the presence of a magnetic field B. The dependences of the dc voltage on the applied magnetic field are characterized by a unique delta-like dip at B=0, which depends on the distribution of the areas of the individual loops, and on the bias current. The voltage span of the dip scales proportional to the number of rows simultaneously operating at the same working point. In addition, the voltage response of the 2D-SQIF is sensitive to a field gradient generated by a control line and superimposed to the homogeneous field coil. This feature opens the possibility to use 2D superconducting quantum interference filters as highly sensitive detectors of spatial gradients of magnetic field. 
J. Oppenlaender, P. Caputo, Ch. Haeussler, T. Traeuble, J. Tomes, A.   Friesch, N. Schopohl