1. a Joint Chair for Experimental Physics of Technical University Budapest and of KFKI Research Institute for Materials Science , H-1525 , Budapest , P.O.B. 49, Hungary
2. b Shanghai Institute of Metallurgy , Shanghai , 200050 , China
3. c GE-TUNGSRAM Co. Ltd., Brody I. Research Center , Budapest , Váci út 77, H-1340 , Hungary