1. Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, United Kingdom
2. Research & Development, Seagate Technology, 1 Disc Drive, Springtown Industrial Estate, Derry BT48 0BF, United Kingdom
3. Recording Heads Operation, Seagate Technology, 7801 Computer Avenue South, Bloomington, Minnesota 55435, USA