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Phys. Rev. B 42, 6568–6573 (1990)

[Issue 10 – 1 October 1990 ]

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Static magnetization direction under perpendicular surface anisotropy

R. C. O’Handley and J. P. Woods

Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139

The problem of depth dependence of the magnetization tilt angle theta (z) is solved analytically for an exchange-coupled ferromagnet with dipole energy, applied field, and surface anisotropy K_s. For K_s <= ( pi M²A)^1/2=K_c, the surface magnetization direction remains in the plane, theta _s= theta (0)= pi /2. For K_s >= K_c, the magnetization vector moves out of the surface, initially with d theta _s/dK_s=- [infinity] , then slowly approaches theta _s=0 as K_s approaches infinity. For Fe, K_c is of order 4 erg/cm². The results indicate that a perpendicular component of magnetization at the surface relaxes to its bulk in-plane orientation over a distance that is generally much shorter than the bulk domain-wall width. The surface remanence and initial susceptibility of the surface magnetization for in-plane applied field are calculated and provide useful expressions for interpreting experimental results. The experimentally measured surface magnetization increases linearly with probe sensitivity depth.

©1990 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v42/p6568
DOI: 10.1103/PhysRevB.42.6568
PACS: 75.30.Pd, 75.10.Hk

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