Born 1959 in Medan, Indonesia. Study of Physics at the University of Technology Twente in Enschede, The Netherlands (1977-1985). PhD work with Prof. Dr. G.A. Sawatzky, Solid State Physics Laboratory, University of Groningen, Groningen, The Netherlands (1986-1990). Post Doc at AT & T Bell Laboratories, Murray Hill, USA (1990-1992) and at the University of Michigan, Ann Arbor, USA (1992-1993). Royal Netherlands Academy of Sciences Researcher (1993-1998) and University Docent at the Solid State Physics Laboratory, University of Groningen, Groningen, The Netherlands. C4 Professor, Lehrstuhl für Angewandte Physik at the University of Cologne, Germany (2001-2009). Director and Scientifc member at the Max Planck Institute for Chemical Physics of Solids since Oktober 2009.