Applied Physics A

, Volume 72, Issue 4, pp 463–470

High-resolution magnetic imaging by local tunneling magnetoresistance

  • W. Wulfhekel
  • H.F. Ding
  • W. Lutzke
  • G. Steierl
  • M. Vázquez
  • P. Marín
  • A. Hernando
  • J. Kirschner

DOI: 10.1007/s003390100579

Cite this article as:
Wulfhekel, W., Ding, H., Lutzke, W. et al. Appl Phys A (2001) 72: 463. doi:10.1007/s003390100579

Abstract.

We give an overview over our recent efforts of high-resolution magnetic imaging 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 tunneling current due to the tunneling magnetoresistance effect. These variations are detected with a lock-in amplifier to separate spin-dependent parts from the topographic parts of the tunneling current such that the topography and the magnetic structure of the sample can be recorded simultaneously. Crucial for this method is to avoid mechanical vibrations of the tip, that may also lead to variations in the tunneling current. Exemplary studies of polycrystalline 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 lateral resolution of the order of 1 nm. Further it is demonstrated that besides topography and magnetisation, also local information about the magnetic susceptibility can be obtained.

PACS: 75.60.Ch; 75.30.Pd; 75.50.Kj 

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • W. Wulfhekel
    • 1
  • H.F. Ding
    • 1
  • W. Lutzke
    • 1
  • G. Steierl
    • 1
  • M. Vázquez
    • 2
  • P. Marín
    • 2
  • A. Hernando
    • 2
  • J. Kirschner
    • 1
  1. 1.Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, GermanyDE
  2. 2.Instituto de Magnetismo Aplicado, Apartado de Correos 155, 28230 Las Rozas, Madrid, SpainES