Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 44: Surface Magnetism (jointly with O)
MA 44.9: Vortrag
Donnerstag, 14. März 2013, 17:30–17:45, H3
Temperature-dependent magnetic hysteresis of the differential conductance in spin-polarized scanning tunneling spectroscopy with Fe-coated W tips — •Soo-hyon Phark1, Jeison Fischer1,2, Marco Corbetta1, Dirk Sander1, and Jürgen Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — 2Laboratório de Filmes Finos e Superfícies, Departamento de Física, Universidade Federal de Santa Catarina , Florianópolis, SC, Brazil
We performed spin-polarized scanning tunneling spectroscopy on bilayer high Co islands of the nm size range [1] on Cu(111) for temperatures between 10 and 30 K in magnetic fields oriented normal to the sample surface. We use a W tip, heated to 2200 K in UHV, coated with 40-monolayer Fe. Increasing the temperature from 10 to 30 K, we observe a decline of the switching field of an individual Co island, and a reduced slope of the differential conductance around zero field [2]. The Néel-Brown model for the magnetic reversal process of the Co islands and a superparamagnetic response of the tip magnetization as described by the Langevin function gives a favorable description of the data. We estimate that the tip apex is composed of roughly 200 Fe atoms. This suggests that a Fe cluster, rather than a Fe film, determines that magnetic response of the tip. The role of the magnetic stray field of the Co island for the magnetic response of the tip is discussed.
[1] Ouazi, Wedekind, Rodary, Oka, Sander, Kirschner, Phys. Rev. Lett. 108, 107206 (2012). [2] Rodary, Wedekind, Sander, Kirschner, Jap. J. Appl. Phys. 47, 9013 (2008).