1. Laboratoire National des Champs Magnétiques Intenses (LNCMI-EMFL), CNRS-UGA-UPS-INSA, 143 Avenue de Rangueil, 31400 Toulouse, France
2. Department of Physics and NUSNNI-Nanocore, National University of Singapore, Singapore 117411
3. School of Physics and CRANN, Trinity College, Dublin 2, Ireland