1. Center for Nanoscience and Nanotechnology (C2N) UMR CNRS – University of Paris‐Sud 10 boulevard Thomas Gobert 91120 Palaiseau France
2. Center for Memory and Recording Research University of California‐San Diego La Jolla CA 92093‐0401 USA
3. Department of Physics University of California‐San Diego La Jolla CA 92093‐0317 USA
4. Advanced Photon Source Argonne National Laboratory Argonne IL 60439 USA
5. Department of Materials Science and Engineering University of California Davis Davis CA 95616 USA