An external magnetic field is picked up by the high temperature superconducting (HTS) concentrator, which determines a Meissner current flow through the superconducting ring;
The HTS concentrator has a constriction which allows an amplification of the field in its vicinity;
A GMR sensor is placed directly above the constriction which allows the measurement of the amplified magnetic field;
In the present project the GMR sensor is placed directly on the HTS ring constriction by the flip-chip technique.
The field amplification factor, A, was calculated as a function of the vertical sensor-HTS constriction distance, z (see below).