We have established a scanning SQUID microscopy user facility as part of the Stanford Nano Shared Facility. The user facility instrument at Stanford is a modification of Attocube’s cryogenic magnetic force microscope. It has a spatial resolution of between 1 and 10 microns, depending on the SQUID sensor mounted. The sample temperature can be varied between 4.2 K and 150 K while scanning. An area of the sample 2.5 mm by 2.5 mm can be accessed in a particular cool-down. Individual areas of up to 150 microns by 150 microns can be scanned in a particular image. Multiple scans can be merged to image larger areas.
There are three imaging modes available: magnetometry, susceptometry, and current imaging. In magnetometry, magnetic fields of a few nanoTesla and dipole moments of a few hundred Bohr magnetons can be detected with a signal-to-noise ratio of 1 in a 1 Hz bandwidth. Similarly, in susceptibility mode a volume susceptibility of a few times 10-7, and in current sensing mode a current of a few nanoAmps can be detected.
- jkirtley [at] stanford.edu
- (650) 492-5090