Evaluation of an STM-SQUID Probe Microscope

We have developed a STM-SQUID probe microscope that combines a SQUID probe microscope and a scanning tunneling microscope (STM). We improved the spatial resolution of the SQUID probe microscope by transmitting the magnetic field to the SQUID by use of a high permeability permalloy probe. It can measure topography of the sample surface and the magnetic field of the sample at the same time using the permalloy probe as a STM probe. In the present study, we have measured the magnetic field distribution generated by a meander line whose line plus spacing were 10 μm. The meander line is useful for estimating the performance of the STM-SQUID probe microscope because we can quantify the magnetic field of a meander line to which a current is applied. We also measured the magnetic field on the sample surface by a magnetic force microscopy (MFM) and compared these measurements to those obtained with the STM-SQUID probe microscope. The MFM measurement was influenced by the sample surface. However, this effect was not observed in the STM-SQUID measurement.