Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 4: Surface Magnetism: Atoms and Molecules
O 4.1: Vortrag
Montag, 7. März 2016, 10:30–10:45, S052
Magnetic Hysteresis in Er trimers on Cu(111) — •Aparajita Singha1, Fabio Donati1, Christian Wäckerlin1, Romana Baltic1, Jan Dreiser1,2, Marina Pivetta1, Stefano Rusponi1, and Harald Brune1 — 1École Polytechnique Fédérale de Lausanne, Switzerland — 2Swiss Light Source, Paul Scherrer Institute, Switzerland
The aim to explore the ultimate density limit of magnetic information storage has triggered increasing interest in surface-supported magnetic nanostructures. Currently the smallest surface-adsorbed ferromagnet consists of only five Fe atoms with magnetic stability up to several hours at 0.3 K [1]. Here, we present evidence of magnetic hysteresis in rare earth Er clusters at 2.5 K starting from the size of three atoms. We combine x-ray magnetic circular dichroism, scanning tunneling microscopy and mean-field nucleation theory to determine the size-dependent magnetic properties of the Er clusters adsorbed on Cu(111). We observe that the magnetization of Er atoms [2] and dimers is oriented in-plane. In contrast, trimers and bigger clusters exhibit out-of-plane anisotropy and a butterfly-shaped magnetic hysteresis at 2.5 K. Their magnetization lifetime is larger than 120 s at 0.1 T.
[1] Khajetoorians et al., Science, 339, 55 (2013) [2] Donati et al., Phys. Rev. Lett., 113, 237201 (2014)