1. Institute of Solid State Physics, University of Latvia, 19 Rainis, Riga, LV-1050, Latvia
2. Institut für Physik, Max-Plank-Institut für Metallforschung, Stuttgart, Germany
3. Institut für Festkörperforschung, Forschungszentrum, Jülich 52425, Germany
4. Department of Basic Sciences, Faculty of Science and Engineering Ishinomaki Senshu University, Ishinomaki 986