Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 46: Surface Magnetism
MA 46.1: Talk
Friday, March 21, 2025, 09:30–09:45, H19
Investigation of the magnetic structure of Eu on W(110) — •Patrick Härtl1, Vijayalaxmi Sankeshwar1,2, Markus Leisegang1, and Matthias Bode1 — 1Physikalisches Institut, Experimentelle Physik II, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany — 2Indian Institute of Science Education and Research(IISER), Pune, Maharashtra 411008, India
Rare earth metal (REM) films are renowned for their complex magnetic properties, primarily governed by the element-specific sign and wavelength of the RKKY interaction. Due to the complexity of their cleaning procedures, the magnetic domain structure of REM surfaces has remained largely unknown until today and is an ongoing topic of debate. In this study, we investigate the structural, electronic, as well as the complex magnetic structure of Europium (Eu) films on W(110) using spin-polarized scanning tunneling microscopy (SP-STM).
In the bulk, Eu has a half-filled 4f- and an empty 5d-shell and adopts a body-centered crystal structure. In thin epitaxial films, however, a metastable hexagonal close-packed structure is expected, accompanied by helical spin ordering below TNéel = 91 K. With optimal preparation conditions, we successfully grew clean, smooth films. In the tunneling spectra of these Eu films we observed two intense peaks at positive bias voltages which we interpret as the unoccupied and exchange-split 5dz2-like surface state. Beyond a critical film thickness, striped regions with a periodicity of ≈3 nm were identified. Experiments with differently magnetized STM tips and the application of an external magnetic field up to ±2.5 T revealed the magnetic nature of the stripes.
Keywords: SP-STM; Rare-Earth Metals; Magnetic structure; Europium; Epitaxial growth