[1] Vienna Tech Univ, Inst Expt Phys, A-1040 Vienna, Austria
[2] Tech Univ Vienna, Inst Theoret Phys, A-1060 Vienna, Austria
[3] CNRS, Grenoble, France
[4] Magnetfabrik Schramberg, Schramberg Sulgen, Germany
[5] VAC, Hanau, Germany
[6] Univ St Martin Dheres, Ensieg LEG, St Martin Dheres, France