1. Department of Physics and Astronomy and Photon Science Institute, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
2. Nano Engineering and Spintronic Technologies Group, Department of Computer Science, The University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
3. The Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Daresbury, Warrington WA4 4AD, United Kingdom