[1] Inst Potosino Invest Cient & Tecnol AC, Div Mat Avanzados, Camino Presa 2055, San Luis Potosi 78216, San Luis Potosi, Mexico
[2] Univ Nacl Autonoma Mexico, Inst Invest Mat, Unidad Morelia, Antigua Carretera Patzcuaro 8701, Morelia 58190, Michoacan, Mexico
[3] Catholic Univ Louvain, Inst Condensed Matter & Nanosci, Pl Croix Sud 1, B-1348 Louvain La Neuve, Belgium