Miniature vector magnetometer for scanning SQUID microscopy
We have demonstrated a miniature vector magnetometer for imaging three orthogonal components of the magnetic field in close proximity to a planar sample. This magnetometer consists of three separate SQUIDs fabricated adjacent to each other on a planar substrate using a planarized, three-level-of-metal low-Tc process with features as small as 0.8 /spl mu/m. The z-axis SQUID has a conventional single square pick-up loop, approximately 10 /spl mu/m in size, that connects to remotely located tunnel junctions via a totally enclosed planar coaxial lead structure. The x- and y-axis SQUIDs are of similar design except that the pick-up structures are in the form of multiple-turn planar solenoids about 10 /spl mu/m in size. In this paper we will discuss the design, fabrication, and characterization of the devices along with initial results of the imaging of individual trapped flux quanta.