Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 93: Surface Magnetism (joint session MA/O)

O 93.1: Invited Talk

Thursday, March 19, 2020, 09:30–10:00, HSZ 101

Vacuum Resonance States as Atomic-Scale Probes of Noncollinear Surface Magnetism — •Anika Schlenhoff — Department of Physics, University of Hamburg (Germany)

Understanding the spin-dependent scattering of electrons at magnetic surfaces is highly relevant for the control of electron transport in future spintronic applications. However, its atomic-scale variations, e.g. on noncollinear magnetic surfaces, remained inaccessible, due to the laterally averaging nature of the established experimental approaches.

By means of spin-polarized scanning tunneling microscopy (SP-STM) and spectroscopy on unoccupied resonance states (RSs) located in vacuo, the reflection of electrons at noncollinear magnetic surfaces is investigated [1]. Even for energies up to 20 eV above the Fermi level, the RSs exhibit the same local spin quantization axis as the underlying spin texture. Mapping the spin-dependent electron phase shift upon reflection at the surface on the atomic scale demonstrates the relevance of all magnetic ground state interactions for the scattering of spin-polarized low-energy electrons. Moreover, while conventional SP-STM is restricted to probe at tip-sample distances of a few Å, tunneling into RSs allows for imaging atomic-scale spin textures at technically feasible distances in the nm regime [2]. Experimental results will be discussed in terms of the RS spin-splitting and the magnetic contrast as a function of bias and tip-sample distance, as well as in terms of the atomic-scale nature of the electron reflection at the surface.

[1] A. Schlenhoff, S. Kovaric, S. Krause, and R. Wiesendanger, Phys. Rev. Lett. 123, 087202 (2019). [2] A. Schlenhoff et al., in preparation.