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Electron-Induced Spin-Crossover in Self-Assembled Tetramers.

Sven Johannsen1, Sascha Ossinger2, Troels Markussen3

  • 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität, 24098 Kiel, Germany.

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|June 16, 2021
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Summary

Spin crossover (SCO) molecules Fe(H2B(pyrazole)(pyridylpyrazole))2 form tetramers on Ag(111). Current injection switches two molecules via spin transitions, with high yields and efficient remote switching observed.

Keywords:
clusterintermolecular energy transfermolecular switchscanning tunneling microscopyspin crossoversurface

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Area of Science:

  • Surface science
  • Molecular magnetism
  • Nanotechnology

Background:

  • Spin crossover (SCO) compounds exhibit bistability, making them promising for molecular switches.
  • Investigating SCO molecule behavior on surfaces is crucial for device applications.

Purpose of the Study:

  • To investigate the spin crossover properties of Fe(H2B(pyrazole)(pyridylpyrazole))2 on Ag(111).
  • To explore the mechanism of current-induced switching and remote switching in molecular tetramers.

Main Methods:

  • Scanning tunneling microscopy (STM) for molecular imaging and manipulation.
  • Current injection for inducing spin transitions.
  • Control experiments using a non-magnetic Zn analog.
  • Density functional theory (DFT) calculations for structural and electronic analysis.

Main Results:

  • Fe(H2B(pyrazole)(pyridylpyrazole))2 molecules form gridlike tetramers on Ag(111).
  • Current injection induces spin transitions in two molecules per tetramer with high efficiency.
  • Remote switching of SCO molecules via neighboring immutable molecules is demonstrated.
  • DFT calculations support the proposed tetramer structure and remote switching mechanism.

Conclusions:

  • The study demonstrates efficient, switchable SCO molecules in a tetrameric assembly on a surface.
  • The findings highlight the potential of such systems for nanoscale electronic devices.
  • A detailed structural model and switching mechanism are proposed and validated.