Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 7: Surface Magnetism and Topological Insulators (joint session MA/TT)
TT 7.5: Talk
Monday, March 9, 2026, 10:30–10:45, POT/0351
Magnetic domain structure of holmium films at low temperatures — •Patrick Härtl1, Vijayalaxmi Sankeshwar2, 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 metals play a central role in modern magnetism, with their behavior largely governed by the element-specific sign and oscillation period of the RKKY interaction. However, real-space investigations of their complex magnetic domain structures remain scarce. Here, we present a systematic study of the structural and magnetic properties of epitaxial holmium (Ho) films grown on W(110), using low-temperature spin-polarized scanning tunneling microscopy (SP-STM).
Bulk Ho crystallizes in a hexagonal close-packed structure and exhibits an exceptionally large magnetic moment of approximately 10 µB, forming a helical spin spiral below TC=20 K.
In our films, we find predominantly ferromagnetic in-plane domains for thicknesses up to about 50 atomic layers (AL), with domain walls strongly pinned to crystalline defects.
For coverages above 50 AL, additional out-of-plane stripe domains emerge, which we attribute to the uncompensated c-axis magnetization of the helical cone state.
Domain wall analysis reveals Néel-capped Bloch-type walls with characteristic widths of roughly ≈1.2 nm (60∘), ≈3 nm (120∘), and ≈4 nm (180∘).
The stripe domains are suppressed by out-of-plane magnetic fields of µ0H = ± 300 mT.
Published in: P. Härtl et al., Phys. Rev. B 112, 174402 (2025).
Keywords: SP-STM; Rare-Earth Magnetism; Domain Structures; Helical Spin Spirals; Holmium