Magnetic Imaging with Nanometer Spatial Resolution Using Spin-Polarized Scanning Tunneling Microscopy

摘要

We have developed spin-polarized scanning tunneling microscopy for magnetic imaging with nanometer-scale resolution. Using normalized-differential conductivity, the magnetic signal is obtained as the product of the spin-polarization of the system and the angle between the two magnetic directions of the tip and sample. For Co(0001) surfaces, the maximum magnetic contrast of approx 23 percent is achieved at bias voltages corresponding to a Co(0001) minority-spin surface state. Images of the magnetic contrast obtained on the Co island films showed domain structures depending on each island element. Since a narrow domain wall with a width of 4 nm is observed in the images, the spatial resolution of this method is estimated to be less than a few nanometers.