1. Physics Department, Federal University of São Carlos 1 , 13565-905 São Carlos, São Paulo, Brazil
2. Department of Physics, University of Richmond 2 , 28 Westhampton Way, Richmond, Virginia 23173, USA
3. 3 Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Lehrstuhl für Technische Physik, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany