About the Authors

Lauri Jetsu

lauri.jetsu@helsinki.fi

Affiliation Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Finland

Sebastian Porceddu

Affiliation Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Finland

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: LJ SP. Performed the experiments: LJ SP. Analyzed the data: LJ SP. Contributed reagents/materials/analysis tools: LJ SP. Wrote the paper: LJ SP.