a
J. Stefan Institute, Solid State Physics Department, Jamova 39, SI-1000 Ljubljana, Slovenia
E-mail: jani.dolinsek@ijs.si
;
Fax: +386 1 4773 191
;
Tel: +386 1 4773 740
b
Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia