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O: Fachverband Oberflächenphysik

O 30: Poster Session - Surface Magnetism

O 30.6: Poster

Montag, 16. März 2020, 18:15–20:00, P1A

The alloy Mn88Ni12: An Intrinsically Spin-Polarised Tip Material? — •J. Rika Simon, Martina Trahms, Jennifer Hartfiel, Gaël Reecht, and Katharina J. Franke — Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany

Spin-polarised tips are necessary for the realisation of electron-spin resonance (ESR) in a scanning tunnelling microscope (STM). These tips are typically obtained by transferring a few magnetic atoms to the tip apex and controlling their magnetisation by an external magnetic field [1]. Recently, Forrester et. al. have suggested Mn88Ni12 as an alternative tip material because of its intrinsic magnetic properties [2]. Moreover, it has been shown very recently by Willke et. al. that the magnetic field created by a spin-polarised tip is sufficient to perform single-atom ESR [3]. Combining both would allow for ESR-setups without the need for an external magnetic field.

We fabricate a Mn88Ni12 tip and investigate its properties using different model systems to study their spin-polarisation: Co nano-islands on Cu(111), and Fe(III)-octaethylporphyrin (FeOEP) on Au(111) and on Pb(111). Our experimental results do not yield unambiguous observation of spin-polarisation. The discrepancy of the results of our measurement techniques to those utilised by Forrester et. al. could be due to differences in preparation and treatment of the tip prior to the measurements, requiring a detailed analysis of the tip fabrication.

[1] M. Bode, Reports on Progress in Physics 66, 523–582 (2003)

[2] P. R. Forrester et al, Rev. Sci. Instrum. 89, 123706 (2018)

[3] P. Willke et al., arXiv: 1908.11061 [cond-mat.mes-hall] (2019)