1. Department of Electrical and Computer EngineeringUniversity of California, San Diego 9500 Gilman Dr La Jolla CA 92093 USA
2. Materials Science and EngineeringUniversity of California, San Diego 9500 Gilman Dr La Jolla CA 92093 USA
3. Center for Memory and Recording ResearchUniversity of California, San Diego 9500 Gilman Dr La Jolla CA 92093 USA