Phys. Rev. Lett. Phys. Rev. A Phys. Rev. B Phys. Rev. C Phys. Rev. D Phys. Rev. E Phys. Rev. ST AB Rev. Mod. Phys. Phys. Rev. (Series I) Phys. Rev. Volume: Page/Article:

Phys. Rev. B 43, 780–787 (1991)

[Issue 1 – 1 January 1991 ]

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Giant monolayer magnetization of Fe on MgO: A nearly ideal two-dimensional magnetic system

Chun Li and A. J. Freeman

Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208-3112

Studies of the structural, electronic, and magnetic properties of a model 3d ferromagnetic metal-ceramic interface system Fe/MgO(001) by the full-potential linearized augmented-plane-wave total-energy method are reported. Surprisingly, the electronic and magnetic properties of a monolayer of Fe on MgO(001) substrate (magnetic moment M=3.07µ_B) are remarkably close to that of a free-standing Fe monolayer (with a giant moment M=3.10µ_B), as a result of the lack of electronic interaction between Fe and MgO. (The charge transfer at the Fe/MgO interface is less than 0.05 e/atom and so any direct chemical interaction between Fe and MgO is unlikely.) Thus, this system might be an ideal two-dimensional system for studying other phenomena such as magnetic anisotropy, phase transitions, and critical behavior. For two layers of Fe on MgO, i.e., 2Fe/MgO(001), the top layer Fe(M=2.96µ_B) shows features close to that of a free bcc Fe(001) surface (M=2.96µ_B). Significantly, the magnetic moment of the Fe layer that interfaces the MgO substrate (M=2.85µ_B) is also largely enhanced from the subsurface moment (2.35µ_B) in bcc Fe(001), again indicating an extremely weak effect from the MgO substrate.

©1991 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v43/p780
DOI: 10.1103/PhysRevB.43.780
PACS: 75.70.Ak, 73.40.Ns

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References

1. T. Kanaji, K. Asano and S. Nagata, Vacuum 23, 55 (1973) [ INSPEC].
2. T. Kanaji, T. Kagotani and S. Nagata, Thin Solid Films 32, 217 (1976) [ INSPEC].
3. T. Urano and T. Kanaji, J. Phys. Soc. Jpn. 57, 3043 (1988) [ INSPEC].
4. R. A. Hubert and J. M. Gilles, Appl. Surf. Sci. 22/23, 631 (1985).
5. M. Naga, N. Tanaka and K. Mihama, Jpn. J. Appl. Phys. 2 Lett. 25, L614 (1986).
6. M. Boudart, A. Delbouille, J. A. Dumesic, S. Khammouma and H. Topsoe, J. Catalysis 37, 486 (1975); and,, 503 (1975); and,, 513 (1975).
7. Chun Li, A. J. Freeman, and C. L. Fu (unpublished).
8. E. Wimmer, H. Krakauer, M. Weinert and A. J. Freeman, Phys. Rev. B 24, 864 (1981), and references therein.
9. W. Kohn and L. F. Sham, Phys. Rev. 140, A1133 (1965).
10. V. von Barth and L. Hedin, J. Phys. C 5, 1629 (1972) [ INSPEC].
11. S. Ohnishi, A. J. Freeman and M. Weinert, Phys. Rev. B 28, 6741 (1983).
12. The 2D lattice constant of MgO(001) is app3% larger than that of bcc Fe(001). Generally, such expanded lattice constant results in slight enhancement of the local magnetic moment of 3d ferromagnetic metals ( app 0.02 µ_B enhancement at 3% lattice expansion for Fe systems). However, we used a smaller radius, 2.20 a.u., for the Fe atoms in both 1Fe/MgO and 2Fe/MgO (to allow relaxation of the Fe-MgO interlayer spacing), compared with that used in the bcc Fe(001) surface calculation, 2.34 a.u. The change in the magnetic moment of 2Fe/MgO by taking the smaller MT radius is app 0.01 µ_B. Thus, despite these slightly different factors, the surface Fe of 2Fe/MgO shows no significant difference in magnetic moment compared with that of a free bcc Fe(001) surface atom.
13. A. J. Freeman and C. L. Fu, J. Appl. Phys. 61, 3356 (1987) [ SPIN][ INSPEC]; C. Li, A. J. Freeman and C. L. Fu, J. Magn. Magn. Mater. 75, 201 (1988) [ INSPEC].
14. Chun Li, A. J. Freeman, H. J. F. Jansen and C. L. Fu, Phys. Rev. B 42, 5433 (1990); Chun Li, A. J. Freeman and C. L. Fu, J. Magn. Magn. Mater. 83, 51 (1990) [ INSPEC].

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