Scanning SQUID probe microscope with STM and AFM

Abstract

Scanning SQUID microscopy (SSM) has been developed in some groups to achieve both of the good spatial resolution and quantitative accuracy for magnetic imaging. We have developed scanning SQUID probe microscope using a fine permalloy probe and a high Tc superconducting (HTS) SQUID. The microscope has two modes, a scanning tunneling microscope (STM)-SQUID mode for conductive materials and an atomic force microscope (AFM)-SQUID mode even for insulating ones. The submicron magnetic domains of ferromagnetic thin films, fine magnetic patterns of magnetic hard disk and magneto-optical disk, and so on were clearly observed. The STM-SQUID has achieved the imaging of surface morphology with nanometer scale and magnetic field with submicron scale simultaneously, whereas the AFM-SQUID can achieve the comparable performance to the STM-SQUID even in insulating samples. It indicates that the scanning SQUID probe microscope with STM and AFM has good performance to measure fine magnetic field distribution on both conductor and insulator samples.