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Single-atom electron paramagnetic resonance in a scanning tunneling microscope driven by a radio-frequency antenna at 4 K

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Seifert T. S., Kovarik S., Nistor C., Persichetti L., Stepanow S., Gambardella P.,
Project Spin-orbitronics in ferromagnets and antiferromagnets
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Original article (peer-reviewed)

Journal Physical Review Research
Volume (Issue) 2(1)
Page(s) 013032 - 013032
Title of proceedings Physical Review Research
DOI 10.1103/physrevresearch.2.013032

Open Access

URL https://link.aps.org/doi/10.1103/PhysRevResearch.2.013032
Type of Open Access Repository (Green Open Access)

Abstract

Combining electron paramagnetic resonance (EPR) with scanning tunneling microscopy (STM) enables detailed insight into the interactions and magnetic properties of single atoms on surfaces. A requirement for EPR-STM is the efficient coupling of microwave excitations to the tunnel junction. Here, we achieve a coupling efficiency of the order of unity by using a radio-frequency antenna placed parallel to the STM tip, which we interpret using a simple capacitive-coupling model. We further demonstrate the possibility to perform EPR-STM routinely above 4 K using amplitude as well as frequency modulation of the radio-frequency excitation. We directly compare different acquisition modes on hydrogenated Ti atoms and highlight the advantages of frequency and magnetic-field sweeps as well as amplitude and frequency modulation in order to maximize the EPR signal. The possibility to tune the microwave-excitation scheme and to perform EPR-STM at relatively high temperature and high power opens this technique to a broad range of experiments, ranging from pulsed EPR spectroscopy to coherent spin manipulation of single-atom ensembles.
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