Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 5: Hauptvortr
äge Hesse / A. Bauer

MA 5.2: Invited Talk

Monday, March 8, 2004, 14:30–15:00, H10

Breakthrough in magneto-optical near-field microscopy — •Andreas Bauer, Gereon Meyer, Tristan Crecelius, Irene Mauch, and Günter Kaindl — Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin

Magneto-optical microscopy is a powerful technique for studying magnetic properties of thin films. The major drawback of conventional optical microscopy, however, is the diffraction-limited spatial resolution, which renders studies of sub-µm structures difficult. Rather promising was therefore the development of scanning near-field optical microscopy (SNOM) almost two decades ago by which resolutions beyond the diffraction limit could be achieved. However, due to persistent technical problems such as diminished magneto-optical signals caused by depolarisation effects, magnetic SNOM is still not established as a high-resolution magnetic-microscopy technique.

We have constructed a magnetic SNOM that overcomes most of the problems [1]. It can be operated either in air or ultrahigh vacuum, at variable sample temperature and external magnetic fields. Its resolution and sensitivity is high enough to allow for imaging of a few hundred nm-wide magnetic-stripe domains in ultrathin films of Fe/Cu(100). We also studied the transformation of the stripe-domain phase in external magnetic fields. The high sensitivity as well as suppression of artefacts is provided by a Sagnac interferometer which is a unique technique for detecting magneto-optical effects. The Sagnac-SNOM should also be ideally suited for ultrafast magnetization-dynamics measurements of nanostructures.

[1]  G. Meyer et al., Appl. Phys. Lett. 83, 1394 (2003).