1. School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK.
2. Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00 Praha 6, Czech Republic.
3. Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic.
4. Diamond Light Source, Chilton, Didcot, Oxfordshire, OX11 0DE, UK.
5. Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
6. Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0HE, UK.
7. Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany.
8. Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Praha 8, Czech Republic.
9. Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, PL-02-668 Warsaw, Poland.