Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 53: Spin Structures at Surfaces and in thin films II

MA 53.10: Vortrag

Freitag, 4. April 2014, 11:45–12:00, BEY 118

Enhanced atomic-scale spin contrast due to spin friction — •Safia Ouazi, André Kubetzka, Kirsten von Bergmann, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, 20355 Hamburg, Germany

We report that atomic-scale magnetic contrast can be enhanced by one order of magnitude when a magnetic adatom is controllably trapped between a scanning tunneling microscope tip and a magnetic substrate during scanning. As model system, we study the (√3× √3)R30^∘ magnetic superstructure of a monolayer Fe on Re(0001), with low-temperature spin-polarized scanning tunneling microscope measurements (SP-STM). The observed in-plane Néel ordered state has a magnetic unit cell of three atoms. We obtain magnetic atom manipulation images from the tunneling regime to almost contact regime by systematically varying the gap resistance. This parameter determines the tip-sample distance and tunes the magnetic interactions between the tip, sample and the magnetic adatom. At intermediate gap resistance, we observe that the motion of the manipulated atom depends on the spin alignment of the magnetic layer and consider this a manifestation of spin friction, as in [1]. We discuss the role of tip-sample distance for the observation of the magnetic structure of the sample and the mechanism for the boost of magnetic corrugation.

[1] Wolter, B. et al, Phys. Rev. Lett. 109, 116102 (2012)