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Physical Review B (Condensed Matter and Materials Physics) -- April 1, 1998 -- Volume 57, Issue 13 pp. 7814-7822

Micromagnetic structures and microscopic magnetization-reversal processes in epitaxial Fe/GaAs(001) elements

E. Gu, E. Ahmad, J. A. C. Bland, and L. M. Brown

Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom

M. Rührig, A. J. McGibbon, and J. N. Chapman

Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, United Kingdom

(Received 23 June 1997)

The in-plane size and orientation-dependent micromagnetic structures of thin epitaxial Fe(001) elements were studied by Lorentz electron microscopy. It is found that the single-domain remanent state supported by continuous epitaxial films with in-plane anisotropy decays into a multidomain configuration upon reducing the film lateral dimensions. For 150-Å-thick Fe(001) elements, such drastic changes in the remanent domain structure and reversal processes occur when the element size is reduced to ~ 10 µm. This transition can be explained as a consequence of the in-plane dipolar (shape anisotropy) contribution to the total energy becoming comparable with that of the magnetocrystalline anisotropy at this size. Due to the interplay between in-plane shape and magnetocrystalline anisotropies, novel micromagnetic phenomena were observed. Distinct microscopic reversal processes arise according to not only the crystallographic direction along which the field is applied but also the orientation of the element edges. For magnetization reversal along the in-plane 100 directions (easy axes), domains nucleate at either element edges or corners depending on the orientation of element edges. For applied fields aligned along the in-plane 110 directions (hard axes), a fine-scale stripe (width 200 nm) domain structure develops upon reducing the applied field from saturation. In addition to coherent rotation and domain-wall displacement, a 90° coherent jump reversal process has been observed for the elements with edges parallel to the 110 directions. The micromagnetic behavior of these epitaxial elements is substantially different from those of either continuous epitaxial Fe(001) films [E. Gu et al., Phys. Rev. B 51, 3596 (1995), C. Daboo et al., Phys. Rev. B 51, 15 964 (1995)] or polycrystalline elements in which the magnetocrystalline anisotropy is negligibly small. As the relative contributions of the in-plane shape and magnetocrystalline anisotropies can be modified by varying the element size, shape and orientation, these mesoscopic epitaxial elements not only offer an ideal model to study the roles of anisotropies in determining the micromagnetic structures but also allow the magnetic spin configuration to be controlled which could be useful for device applications, e.g., spin-polarized injection contacts and magnetic memory elements. [G. A. Prinz, Physics Today 48(4), 58 (1995)]. ©1998 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v57/p7814
PACS: 75.30.Gw, 68.55.-a, 75.70.Kw        Additional Information

References

1. R. Allenspach and A. Bischof, Phys. Rev. Lett. 69, 3385 (1992). [ISI]
   
2. R. Allenspach, M. Stampanoni, and A. Bischof, Phys. Rev. Lett. 65, 3344 (1990). [ISI]
   
3. M. Speckmann, H. P. Oepen, and H. Ibach, Phys. Rev. Lett. 75, 2035 (1995). [ISI]
   
4. G. Bochi, H. J. Hug, D. I. Paul, B. Stiefel, A. Moser, I. Parashikov, H. J. Guntherodt, and R. C. O'Handley, Phys. Rev. Lett. 75, 1839 (1995). [ISI]
   
5. G. Bochi, C. A. Ballentine, H. E. Inglefield, C. V. Thompson, R. C. O'Handley, H. J. Hug, B. Stiefel, A. Moser, and H. J. Güntherodt, Phys. Rev. B 52, 7311 (1995). [ISI]
   
6. C. Kittel, Phys. Rev. 70, 965 (1946). [ISI]
   
7. R. Allenspach, J. Magn. Magn. Mater. 129, 160 (1994). [INSPEC] [ISI]
   
8. J. L. Robins, R. J. Celotta, J. Unguris, D. T. Pierce, B. T. Jonker, and G. A. Prinz, Appl. Phys. Lett. 52, 1918 (1988). [SPIN] [ISI]
   
9. H. P. Oepen, J. Magn. Magn. Mater. 93, 116 (1991). [INSPEC] [ISI]
   
10. E. Gu, J. A. C. Bland, C. Daboo, M. Gester, L. M. Brown, R. Ploessl, and J. N. Chapman, Phys. Rev. B 51, 3596 (1995). [ISI]
    
11. C. Daboo, R. J. Hicken, E. Gu, M. Gester, S. Gray, E. Ahmad, J. A. C. Bland, R. Ploessl, and J. N. Chapman, Phys. Rev. B 51, 15 964 (1995). [ISI]
    
12. E. Gu, C. Daboo, J. A. C. Bland, M. Gester, A. J. R. Ives, L. M. Brown, N. A. Stelmashenko, and J. N. Chapman, J. Magn. Magn. Mater. 126, 180 (1993). [INSPEC] [ISI]
    
13. G. A. Prinz, Phys. Today 48 (4), 58 (1995). [SPIN] [ISI]
    
14. D. A. Herman, Jr., B. E. Argyle, and B. Petek, J. Appl. Phys. 61, 4200 (1987). [SPIN] [ISI]
    
15. B. W. Corb, J. Appl. Phys. 63, 2941 (1988). [SPIN] [ISI]
    
16. E. J. Ozimek, J. Appl. Phys. 57, 5406 (1985). [SPIN] [ISI]
    
17. S. McVitie and J. N. Chapman, IEEE Trans. Magn. 24, 1778 (1988). [INSPEC] [ISI]
    
18. S. J. Hefferman, J. N. Chapman, and S. McVitie, J. Magn. Magn. Mater. 95, 76 (1991). [INSPEC] [ISI]
    
19. U. Resch, N. Esser, Y. S. Raptis, W. Richter, J. Wasserfall, A. Forster, and D. I. Weatwood, Surf. Sci. 269, 797 (1992). [INSPEC]
    
20. J. Yuan, E. Gu, M. Gester, J. A. C. Bland, and L. M. Brown, J. Appl. Phys. 75, 6501 (1994). [SPIN] [ISI]
    
21. R. J. Hicken, D. E. P. Eley, M. Gester, S. J. Gray, C. Daboo, A. J. R. Ives, and J. A. C. Bland, J. Magn. Magn. Mater. 145, 278 (1995) (ScienceDirect). [INSPEC] [ISI]
    
22. J. J. Krebs, B. T. Jonker, and G. A. Prinz, J. Appl. Phys. 61, 2596 (1987). [SPIN] [ISI]
    
23. M. Gester, C. Daboo, R. J. Hicken, S. J. Gray, A. Ercole, and J. A. C. Bland, J. Appl. Phys. 80, 347 (1996). [SPIN] [ISI]
    
24. J. N. Chapman, J. Phys. D 17, 623 (1984). [INSPEC] [ISI]
    
25. J. N. Chapman, S. McVitie, and S. J. Hefferman, J. Appl. Phys. 69, 6078 (1991). [SPIN] [ISI]
    
26. E. Gu, E. Ahmad, S. J. Gray, C. Daboo, J. A. C. Bland, L. M. Brown, M. Rührig, A. J. McGibbon, and J. N. Chapman, Phys. Rev. Lett. 78, 1158 (1997). [ISI]
    
27. U. Ebels, M. Gester, C. Daboo, and J. A. C. Bland, Thin Solid Films 275, 172 (1996) (ScienceDirect). [INSPEC] [ISI]
    

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