Microstructure, magnetic, and magneto-optical properties of chemical synthesized Co-RE (RE=Ho, Er, Tm, Yb, Lu) ferrite nanocrystalline films

The sol-gel synthesis of Co-RE (RE=Ho, Er, Tm, Yb, Lu) ferrite nanocrystall ine films was accomplished on monocrystalline silicon substrates, and the i nfluence of RE ions on structure, magnetic, and magneto-optical (MO) proper ties of the resultant ferrites was examined. The results obtained reveal th at, when x less than or equal to 0.2, the CoFe2-xRExO4 ferrite films have p ure spinel phase with slightly enlarged cell constants and lattice distorti on due to the large radii of RE ions. The RE ions tend to decrease the room -temperature magnetization as well as the Curie point of products, and may have a certain contribution to coercive force except for a nonmagnetic Lu3 ion. For the present optical structure in which MO layers are substrated o n silica, Co-RE ferrite films show the peak Kerr rotation at a shorter wave length than the CoFe2O4 film, and Er or Tm doped samples exhibit an interes ting enhancement of the MO effect. (C) 1999 American Institute of Physics. [S0021-8979(99)09217-8].