Mössbauer spectroscopy study of Al distribution in BaAlxFe12−xO19 thin films

Barium hexagonal ferrite (BaM) films grown on Si are a good candidate material for new-generations of on-wafer microwave devices operating at frequencies above 40 GHz. Doping BaM with Al increases the value of anisotropy field even more, and in combination with a large value of remanence, would allow one to create a self-biasing material/structure that would eliminate the need for permanent bias magnets in millimeter wave devices. To examine the occupation of Fe sublattices by Al ions, we carried out Conversion Electron Mossbauer Spectroscopy (CEMS) measurements at room temperature and zero magnetic field (after magnetizing the samples in a strong magnetic field). The spectra can be reasonably fitted with three components (sub-spectra) corresponding to different Fe sublattices. There are significant changes in the spectra with the addition of Al: The magnetic hyperfine field decreases for all three components, and their relative contributions also change remarkably. These observations are in agreement with the fact that the Al substitutes Fe, thus lowering the component contributions and the value of the hyperfine field. In addition, our previous XRD analysis indicates increasing grain misalignment with Al content, further supporting the CEMS data.

[1]  Daming Chen,et al.  Physical properties of Al doped Ba hexagonal ferrite thin films , 2013 .

[2]  Z. Celinski,et al.  Al doped Ba hexaferrite (BaAlxFe12-xO19) thin films on Pt using metallo-organic decomposition , 2012 .

[3]  G. Srinivasan,et al.  Al substituted Ba-hexaferrite single-crystal films for millimeter-wave devices , 2009 .

[4]  V. V. Mamedov,et al.  Study of the magnetic properties of the permanent magnets by Mössbauer spectroscopy , 2009 .

[5]  P. Lukanov,et al.  Influence of microstructure and preparation methods on the magneto-crystalline structure and magnetic properties of submicron barium hexaferrite powders , 2006 .

[6]  Haigen Shen,et al.  Effect of aluminum substitution on microwave absorption properties of barium hexaferrite , 2005 .

[7]  D. Choi,et al.  Site occupancy and anisotropy distribution of Al substituted Ba‐ferrite with high coercivity , 2004 .

[8]  D. Choi,et al.  Mo/spl uml/ssbauer studies and magnetic properties of BaFe/sub 12-x/Al/sub x/O/sub 19/ grown by a wet chemical process , 2003, Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401).

[9]  Siyuan Zhang,et al.  Mössbauer spectroscopy and chemical bonds in BaFe12O19 hexaferrite , 2003 .

[10]  G. Albanese.  Mössbauer investigation of aluminium substituted barium hexaferrite in the paramagnetic state , 1995 .

[11]  D. J. D. Bitetto,et al.  Magnetic Materials for Use at High Microwave Frequencies (50–90 kMc/sec) , 1958 .

[12]  A. Mones,et al.  Cation substitutions in BaFe12O19 , 1958 .