About the Authors

Alfonso Pérez-Escudero

alfonso.perez.escudero@cajal.csic.es (APE); gonzalo.polavieja@cajal.csic.es (GGdP)

Affiliations Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain, Department of Theoretical Physics and Instituto “Nicolás Cabrera” de Física de Materiales, Universidad Autónoma de Madrid, Madrid, Spain

Gonzalo G. de Polavieja

alfonso.perez.escudero@cajal.csic.es (APE); gonzalo.polavieja@cajal.csic.es (GGdP)

Affiliations Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain, Department of Theoretical Physics and Instituto “Nicolás Cabrera” de Física de Materiales, Universidad Autónoma de Madrid, Madrid, Spain

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: APE GGdP. Performed the experiments: APE GGdP. Analyzed the data: APE GGdP. Wrote the paper: APE GGdP.