1. Materials Department, University of Oxford, Parks Road, Oxford OX1 3PH, England
2. INM - Leibniz Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
3. British Heart Foundation Experimental Magnetic Resonance Unit, Wellcome Trust Centre for Human Genetics, Roosevelt Drive, Oxford OX3 7BN, England
4. Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585, Japan
5. Departamento de Imágenes por Resonancia Magnética, Cuban Neurosciences Center, Street 190 e/25 and 27, Cubanacan
Playa, Havana CP 11600, Cuba
6. Advanced Microscopy Laboratory, Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Dublin 2, Ireland
7. School of Physics, Trinity College Dublin, Dublin 2, Ireland
8. Department of Material Science and Engineering, Tokyo Institute of Technology, S8-25, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan
9. Williams Advanced Engineering, Grove, Oxfordshire, OX12 0DQ, England