[1] Univ Gottingen, Inst Phys, D-37077 Gottingen, Germany
[2] Ernst Moritz Arndt Univ Greifswald, Inst Phys, D-17489 Greifswald, Germany
[3] Univ Gottingen, Inst Phys 4, D-37077 Gottingen, Germany
[4] Univ Gottingen, CRC 1073, D-37077 Gottingen, Germany
[5] Univ Bielefeld, Ctr Spinelect Mat & Devices, D-33615 Bielefeld, Germany
[6] Ewha Womans Univ, Dept Phys, Seoul 120750, South Korea