1. James Watt School of Engineering, Electronics & Nanoscale Engineering Division University of Glasgow Glasgow G12 8QQ UK
2. Department of Physics Columbia University New York NY 10027 USA
3. School of Mathematical and Physical Sciences The University of Newcastle Callaghan NSW 2308 Australia
4. Center for Magnetism and Magnetic Materials Department of Physics and Energy Science University of Colorado Colorado Springs Colorado Springs CO 80918 USA