| AVS 55th International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Tuesday Sessions |
| Session MI+NC-TuA |
| Session: | Magnetic Microscopy and Magnetization Dynamics |
| Presenter: | U. Kaiser, University of Hamburg, Germany |
| Authors: | U. Kaiser, University of Hamburg, Germany A. Schwarz, University of Hamburg, Germany R. Wiesendanger, University of Hamburg, Germany |
| Correspondent: | Click to Email |
Magnetic Exchange Force Microscopy (MExFM) is a novel technique that allows magnetic imaging of surfaces with atomic resolution. The set-up of this microscope resembles that of a conventional atomic force microscope, but a magnetic probe tip is used to study short-ranged magnetic exchange forces between the foremost tip atom and the underlying sample atoms. Since MExFM is sensitive to the forces between tip and sample, it is not limited to well-conducting materials like spin polarized scanning tunneling microscopy (SP-STM).1 In our study we investigated the (001) surface of the antiferromagnetic insulator NiO with an iron-coated tip.2 The microscope was operated in ultrahigh vacuum at 8 K in an externally applied magnetic field with a flux density of 5 T. All measurements were performed in the non-contact attractive force regime between tip and sample using the frequency modulation technique. At small tip sample separations we imaged the surface oxygen and nickel atoms with an additional atomic scale modulation on neighboring rows of nickel atoms. This corresponds with the antiferromagnetic arrangement of the nickel atomic magnetic moments. Since all surface nickel atoms are structurally and chemically equivalent, we can unambiguously assign the observed contrast modulation to a magnetic exchange force between tip and sample. In this talk experimental prerequisites for this new method as well as the origin of the exchange interaction are discussed.
1 M. Bode, Rep. Prog. Phys. 66, 523 (2003)
2 U. Kaiser, A. Schwarz, and R. Wiesendanger, Nature 446, 522 (2007)