High-resolution magnetic imaging by local tunneling magnetoresistance

Citation
W. Wulfhekel et al., High-resolution magnetic imaging by local tunneling magnetoresistance, APPL PHYS A, 72(4), 2001, pp. 463-470
Citations number
36
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
ISSN journal
0947-8396 → ACNP
Volume
72
Issue
4
Year of publication
2001
Pages
463 - 470
Database
ISI
SICI code
0947-8396(200104)72:4<463:HMIBLT>2.0.ZU;2-C
Abstract
We give an overview over our recent efforts of high-resolution magnetic ima ging using scanning tunneling microscopy with a ferromagnetic tip. Magnetic sensitivity is obtained on the basis of local tunneling magnetoresistance between a soft magnetic tip and the sample. The magnetisation of the tip is switched periodically with a small coil, leading to variations of the tunn eling current due to the tunneling magnetoresistance effect. These variatio ns are detected with a lock-in amplifier to separate spin-dependent parts f rom the topographic parts of the tunneling current such that the topography and the magnetic structure of the sample can be recorded simultaneously. C rucial for this method is to avoid mechanical vibrations of the tip, that m ay also lead to variations in the tunneling current. Exemplary studies of p olycrystalline Ni and the closure domain pattern of Co(0001) are presented, showing high contrast at acquisition times as low as 3 ms/pixel and a late ral resolution of the order of 1 nm. Further it is demonstrated that beside s topography and magnetisation, also local information about the magnetic s usceptibility can be obtained.