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Journal of Applied Physics -- May 15, 2002 -- Volume 91, Issue 10, pp. 6887-6889

Magnetic force microscope study of antiferromagnet-ferromagnet exchange coupled films

Taras Pokhil, Dian Song, and Eric Linville

Seagate, 7801 Computer Avenue S., Minneapolis, Minnesota 55435

Magnetic microstructure in micron and submicron size elements made of bilayer antiferromagnet-ferromagnet (AFM/FM) (AFM: NiMn, PtMn, and IrMn; FM: NiFe and CoFe) exchange coupled polycrystalline films have been studied using a magnetic force microscope. AFM/FM elements with various thickness of FM layer (50-500 A) have been examined and compared with nonexchange biased FM elements of the same size, shape, and thickness. Micromagnetic structures observed in AFM/FM elements with thick (>200 A) FM layer indicated that, in addition to unidirectional anisotropy, the AFM layer induces uniaxial anisotropy in a FM layer. Bilayers with a NiMn or PtMn AFM layer exhibited higher induced uniaxial anisotropy than ones with IrMn. In the elements with a thin (<100 A) FM layer and NiMn or PtMn as an AFM layer, a local switching of the magnetization direction under an external applied field has been observed. The size of the "switched" areas depends on the material and thickness of the FM and AFM layers. No local switching, just slight rippling of magnetization in the FM, was observed in the samples with an IrMn AFM layer. The results can be explained using either the model of thermally activated switching of AFM grains or the model of induced uniaxial anisotropy at the AFM/FM interface suggesting local variations of induced uniaxial anisotropy. In both models, the in-plane exchange in the FM layer has to be taken into account. ©2002 American Institute of Physics.

doi:10.1063/1.1452225
PACS: 75.70.Cn, 75.50.Ee, 75.50.Bb, 75.30.Et, 75.30.Gw, 75.60.Ej, 81.05.Bx        Additional Information

References

1. W. H. Meiklejohn and C. P. Bean, Phys. Rev. 102, 1413 (1956);
   105, 904 (1957).
   
2. D. Mauri, H. C. Seigmann, P. S. Bagus, and E. Kay, J. Appl. Phys. 62, 3047 (1987).
   
3. A. P. Malozemoff, J. Appl. Phys. 63, 3874 (1988).
   
4. N. C. Koon, Phys. Rev. Lett. 78, 4865 (1997).
   
5. K. Takano, R. H. Kodama, A. E. Berkowitz, W. Cao, and G. Thomas, Phys. Rev. Lett. 79, 1130 (1997).
   
6. V. I. Nikitenkio, V. S. Gornakov, L. M. Dedukh, Y. P. Kabanov, A. F. Khapikov, A. J. Shapiro, R. D. Shull, A. Chaiken, and R. P. Michel, J. Appl. Phys. 83, 6828 (1998).
   
7. T. C. Schulthess and W. H. Butler, J. Appl. Phys. 85, 5510 (1999).
   
8. T. Pokhil, S. Mao, and A. Mack, J. Appl. Phys. 85, 4916 (1999).
   
9. E. Fulcomer and S. H. Charap, J. Appl. Phys. 43, 4190 (1972). [INSPEC]
   
10. C. Hou, H. Fujiwara, and F. Ueda, J. Magn. Magn. Mater. 198, 450 (1999). [INSPEC]
    

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