1. School of Chemistry University College Dublin Belfield Dublin 4 Ireland
2. Univ Rennes CNRS, IPR (Institut de Physique de Rennes)—UMR 6251 35000 Rennes France
3. Current address: Technische Universität Kaiserslautern Kaiserslautern Germany
4. Department of Physics Auburn University Auburn AL 36849 USA
5. Current address: National High Magnetic Field Lab at Florida State University Tallahassee FL USA
6. National High Magnetic Field Laboratory Los Alamos National Laboratory Los Alamos NM 87545 USA
7. Current address: Idaho National Laboratory Idaho Falls ID USA
8. Centre for Nanostructured Media School of Mathematics and Physics Queen's University of Belfast Belfast BT7 1NN, Northern Ireland UK
9. Department of Earth Sciences University of Cambridge Downing Street Cambridge CB2 3EQ UK