Imaging magnetic nanostructures by spin-polarized scanning tunneling spectroscopy

Spin-polarized scanning tunneling spectroscopy (SP-STS) using Gd- and Fe-coated probe tips is investigated. The antiferromagnetic domain structure of perpendicularly magnetized Fe nanowires is imaged by using Gd-coated tips. The influence of an external magnetic field on the nanowire domain structure is demonstrated. Magnetic saturation of the sample is observed at about 450 mT. While Gd-coated tips are sensitive to the out-of-plane magnetization direction, the Fe thin film tips were found to be magnetized in-plane, i.e. perpendicular to the tip axis. our results indicate that the shape anisotropy of our thin film tips plays a minor role compared to the interface anisotropies at the tip apex. (C) 2001 Elsevier Science B.V. All rights reserved.