1. Department of Chemistry, KAIST, Daejeon 305-701, Korea
2. Center for Electricity and Magnetism, KRISS, Daejeon
305-600
3. Nano Materials Research
Team, KBSI, Daejeon 305-333,
Korea
4. Measurement and Analysis
Team, National Nanofab Center, Daejeon
305-806, Korea
5. Spin Convergence
Research Center, KIST, Seoul
136-791, Korea
6. Department of Electrical
Engineering, University of California,
Los Angeles, California 90095,
United States