Magnetite, the oldest magnetic material known, is still important for different fields and applications. Some of its basic properties remain elusive. We have determined the magnetic domain structure of its (100) surface.

Magnetite, in spite of being the oldest magnetic material known by humankind, is still highly relevant in fields ranging from from paleomagnetism to applications in spintronics, due to its high conductivity, chemical stability, high Curie temperature and predicted half-metallic character. In this work, we have determined the magnetic domain structure of the Fe3O4(110) surface by means of X-ray Magnetic Circular Dichroism (XMCD) in X-ray Photoemission Electron Microscopy (PEEM). The (110), high-symmetry crystallographic surface of magnetite is relevant because it contains two ⟨111⟩-type bulk easy axes; nevertheless, it had not been previously studied in detail, in contrast to, e.g. the (001) orientation which does not contain such bulk easy axes. The surface cleanliness and structural order of a the Fe3O4(110) crystal was checked by Low-Energy Electron Microscopy and Diffraction (LEEM and LEED). After sputtering and annealing, a well-defined surface was achieved. This preparation method resulted in a one-dimensional reconstruction formed by rows aligned in the [001] direction. By acquiring XMCD PEEM images at various azimuthal angles, the vector magnetization map of the (110) surface was obtained. Domains were observed with their magnetization directions aligned along the two ⟨111⟩-type bulk easy axes within the (110) surface plane, featuring 180◦, 109◦, and 71◦ domain walls. The domain walls are of Néel type. Using the XMCD sum rules we estimated iron spin and orbital magnetic moments of 3.4 μB and 0.6 μB respectively for the reconstructed surface. At the oxygen K edge we observe a dichroic contrast of close to 1%, which is reversed relative to the one detected from octahedral iron at the L3 edge. A. Mandziak, J.E. Prieto, C. Gutiérrez-Cuesta, M.A. Niño, M. Foerster, J. de la Figuera and P. Nita, “Structural and magnetic properties of the Fe3O4 (110) surface”, Sci Rep 15, 10549 (2025) DOI: 10.1038/s41598-025-94599-6. https://doi.org/10.1038/s41598-025-94599-6