Magnetic gradiometer based on magnetic tunnel junctions in magnetic vortex state (vortex MTJ)

A method comprising,

• generating a magnetic field by applying an alternating current (AC) to an excitation coil of a magnetic gradiometer;
• scanning the magnetic gradiometer across a body comprising at least one measurement target, wherein the magnetic gradiometer comprises:
• a printed circuit board (PCB) comprising a first end and a second end separated by a length, wherein the second end is oriented towards one of the at least one measurement targets;
• an excitation coil encircling at least a portion of the PCB;
• and
• a differential sensor comprising:
• a reference magnetic tunneling junction in magnetic vortex state (vortex MTJ) sensor array proximal to the first end;
• and
• a signal vortex MTJ sensor array proximal to the second end,
• wherein the reference vortex MTJ sensor array and the signal vortex MTJ sensor array are separated by a base length;
• and
• generating an output voltage of the magnetic gradiometer in response to scanning the magnetic gradiometer across the body comprising that at least one measurement target, wherein the output voltage is based on a voltage generated by the reference vortex MTJ sensor array's detection of at least an excitation magnetic field and another voltage generated by the signal vortex MTJ sensor array's detection of an excitation magnetic field due to a composition of the body comprising the at least one measurement target.