**Author details**

Matilde García-Valdecasas Ojeda\*, Emilio Romero Jiménez, Sonia R. Gámiz-Fortis, Yolanda Castro-Díez and María Jesús Esteban Parra Department of Applied Physics, University of Granada, Granada, Spain

\*Address all correspondence to: mgvaldecasas@ugr.es

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