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O: Fachverband Oberflächenphysik

O 72: Scanning Probe Techniques I: STM-ESR and Method Development (joint session O/CPP)

O 72.2: Vortrag

Mittwoch, 18. März 2020, 15:15–15:30, TRE Ma

Electron paramagnetic resonance of single Ti and Fe atoms with an out-of-plane magnetic field probed by STM — •Tom S. Seifert¹, Stepan Kovarik¹, Dominik Juraschek^1,2, Nicola A. Spaldin¹, Sebastian Stepanow¹, and Pietro Gambardella¹ — ¹ETH Zurich, Switzerland — ²Harvard University, USA

Combining the sub-atomic resolution of scanning tunneling microscopy (STM) with the spectral resolution of electron-paramagnetic resonance (EPR) allows for sensitive probing magnetic interactions of single atoms on a surface [1]. However, the experimental requirements for driving the EPR transitions are still under debate [2,3]. In-depth understanding of what drives these spin rotations is mandatory to explore novel material systems and optimize the sensitivity of this technique. Here, we acquire EPR spectra of single Fe and hydrogenated Ti atoms on bilayer MgO on Ag using a radio frequency (RF) antenna close to the STM junction with a magnetic field applied perpendicular to the surface [4]. We investigate in a systematic way the impact of RF excitation strength and tunneling parameters on the EPR signal with emphasis on the electric and magnetic fields present at the tunnel junction. This analysis is supported by density functional calculations of the electronic and phononic density of states of the probed systems.

[1] S. Baumann et al., Science 350 (2015) [2] K. Yang, et al., PRL 122 (2019) [3] P. Willke et al., Nano Lett. 19 (2019) [4] T. S. Seifert et al., ArXiv 1908.03379 (2019)