1. Institute of Physics, Johannes Gutenberg-University Mainz, 55128 Mainz, Germany
2. WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
3. Centro de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Departamento de Química-Física, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
4. Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
5. Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
6. Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
7. Department of Applied Physics, The University of Tokyo, Tokyo 113-8656, Japan
8. Institut of Physics, Academy of Sciences of the Czech Republic, Praha 11720, Czech Republic
9. Graduate School of Excellence Materials Science in Mainz, 55128 Mainz, Germany