Regensburg 2007 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 32: Magnetic Imaging

MA 32.1: Vortrag

Freitag, 30. März 2007, 11:00–11:15, H22

Simulation of Spin-Polarized Scanning Tunneling Microscopy Images of Nanoscale Non-Collinear Magnetic Structures — •Stefan Heinze — Institut für Angewandte Physik, Universität Hamburg, Jungiusstrasse 11, 20355 Hamburg

Spin-polarized scanning tunneling microscopy (SP-STM) allows to image magnetic structures with a resolution down to the atomic scale. The interpretation of such measurements is often not trivial and relies on an accurate description of the electronic and magnetic structure of the sample typically provided by density functional theory (DFT) calculations. However, such computationally demanding calculations can become prohibitive on the nanoscale.

Here, we use a simple approach based on the spin-polarized version of the Tersoff-Hamann model and the concept of atom superpositions to simulate SP-STM images [1]. It requires only the knowledge of the atomic scale magnetic structure. In spite of its simplifications, calculated SP-STM images of periodic collinear and non-collinear magnetic structures are in many cases in excellent agreement with experiments and DFT calculations. Especially for surfaces of chemically equivalent atoms the atomic scale SP-STM images are dominated by the magnetic structure and depend much less on the specific electronic structure. This suggests the application of the method to more complex non-collinear magnetic structures such as domain walls in antiferromagnets, spin-spiral states, spin glasses, or disordered states. Based on the model, we study SP-STM images of helical spin-spiral states in ultra-thin films. [1] S.Heinze, Appl. Phys. A 85, 407 (2006).