1. Department
of Physics, University of South Florida, Tampa, Florida 33620, United States
2. BCMaterials, Edificio
No. 500, Parque Tecnológico
de Vizcaya, Derio 48160, Spain
3. Department
of Electricity and Electronics, University of Basque Country (UPV/EHU), Leioa 48940, Spain
4. Department
of Applied Physics II, University of Basque Country (UPV/EHU), Leioa 48940, Spain
5. Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José
2055, Col. Lomas 4a, San Luis Potosí, S.L.P. 78216, México