Spinfinity

Python package for simulating quantum spin systems in tunnel junction experiments.

Intended Use

Spinfinity is intended for researchers working on quantum spin systems in scanning probe microscopy. The package is designed for modeling spin structures in double-barrier tunnel junctions, solving their spin Hamiltonians, and simulating observables that can be compared to experimental spectroscopy data.

Typical use cases include:

• modeling single-spin and multi-spin systems
• calculating eigenenergies and eigenstates of custom spin Hamiltonians
• simulating tunneling-induced transition rates and steady-state populations
• computing differential conductance spectra for comparison with experiment
• computing Electron Spin Resonance spectra and related driven dynamics

References

• Ternes, M., Spin excitations and correlations in scanning tunneling spectroscopy. New J. Phys. 17, 063016 (2015). https://dx.doi.org/10.1088/1367-2630/17/6/063016
• Loth, S., von Bergmann, K., Ternes, M. et al. Controlling the state of quantum spins with electric currents. Nature Phys 6, 340–344 (2010). https://doi.org/10.1038/nphys1616
• Yang, K., Willke, P., Bae, Y. et al. Electrically controlled nuclear polarization of individual atoms. Nature Nanotech 13, 1120–1125 (2018). https://doi.org/10.1038/s41565-018-0296-7
• Yang, K., Phark, SH., Bae, Y. et al. Probing resonating valence bond states in artificial quantum magnets. Nat Commun 12, 993 (2021). https://doi.org/10.1038/s41467-021-21274-5

Citation

If you use Spinfinity in scientific work, please cite the software together with the relevant methodological references listed above.

Suggested citation text:

@software{Spinfinity,
  title   = {Spinfinity: A Python package for simulating quantum spin systems in tunnel junction experiments},
  author  = {Greule, Paul and Arnold, Jonas and Renz, Luise and Hardeweg, Lovis and Matusche, Johanna and Huang, Wantong and Au-Yeung, Kwan Ho and Ascheraden, Hannah and Schwenk, Johannes and Willke, Philip},
  year    = {2026},
  url     = {https://github.com/WillkeLab/Spinfinity}
}

Support

For support please contact: paul.greule@kit.edu

Contributing

We welcome everyone to contribute to this project. Please contact: paul.greule@kit.edu

License

Spinfinity is licensed under the GNU General Public License (GPL). See the repository for the full license text.