Reduction of Read Gap Length by Thin Exchange Bias Layer

For the material design of antiferromagnetic layer enabling to reduce the read gap length of magnetic recording heads, the exchange bias between the ferromagnetic (FM) and antiferromagnetic (AFM) bilayer was investigated within the framework of the classical Heisenberg model. The dependence of the exchange bias on the AFM layer thickness was also calculated using the Landau-Lifshitz-Gilbert equation. The triple-Q (3Q), T1, and AF-I spin structures are obtained in the disordered γ-phase, ordered L12-, and L10-type lattices, respectively. The exchange bias is caused by the formation of the interfacial domain wall in the AFM layer, and the critical thickness dc of the AFM layer is dominated by the varied spin structures. Consequently, the relation of the critical thickness can be represented as √3dc3Q = √2dcT1 = dcAF-I.

[1]  Haiwen Xi,et al.  Antiferromagnetic thickness dependence of exchange biasing , 2000 .

[2]  A. Sakuma,et al.  chapter 4 Magnetic and Electrical Properties of Practical Antiferromagnetic Mn Alloys , 2006 .

[3]  C. Henley.  Ordering by disorder: Ground‐state selection in fcc vector antiferromagnets , 1987 .

[4]  Mark T. Johnson,et al.  Orientational dependence of the exchange biasing in molecular‐beam‐epitaxy‐grown Ni80Fe20/Fe50Mn50 bilayers (invited) , 1994 .

[5]  R. Nakatani,et al.  Exchange Coupling between Antiferromagnetic Mn–Ir and Ferromagnetic Ni–Fe Layers , 1996 .

[6]  Malozemoff.  Random-field model of exchange anisotropy at rough ferromagnetic-antiferromagnetic interfaces. , 1987, Physical review. B, Condensed matter.

[7]  P. Freitas,et al.  Exchange enhancement and thermal anneal in Mn76Ir24 bottom-pinned spin valves , 2001 .

[8]  C. Tsang,et al.  Design, fabrication and testing of spin-valve read heads for high density recording , 1994 .

[9]  M. Takahashi,et al.  Thickness dependence of exchange anisotropy of polycrystalline Mn3Ir/Co-Fe bilayers , 2005 .

[10]  J. K. Howard,et al.  Novel method for determining the anisotropy constant of MnFe in a NiFe/MnFe sandwich , 1987 .

[11]  G. Park,et al.  Magnetoresistance and interlayer diffusion in PtMn spin valves upon postdeposition annealing , 2001 .

[12]  A. Sakuma,et al.  Mechanism of the exchange-bias field in ferromagnetic and antiferromagnetic bilayers , 2003 .

[13]  N. Koon.  Calculations of Exchange Bias in Thin Films with Ferromagnetic/Antiferromagnetic Interfaces , 1997 .

[14]  T. Schulthess,et al.  Consequences of Spin-Flop Coupling in Exchange Biased Films , 1998 .

[15]  Y. Endoh,et al.  Antiferromagnetism of γ Iron Manganes Alloys , 1971 .

[16]  M. Long.  Effects that can stabilise multiple spin-density waves , 1989 .

[17]  A. Sakuma,et al.  Critical Thickness of Antiferromagnetic Layer in Exchange Biasing Bilayer System(Condensed matter: structure and mechanical and thermal properties) , 2008 .

[18]  H. Fujiwara,et al.  Effect of exchange coupling of polycrystalline antiferromagnetic layers on the magnetization behavior of soft magnetic layers , 1999 .

[19]  D. Mauri,et al.  Simple model for thin ferromagnetic films exchange coupled to an antiferromagnetic substrate , 1987 .

[20]  M. Takahashi,et al.  Magnetic anisotropy of antiferromagnet and its role on the exchange bias in ferromagnetic/antiferromagnetic bilayers , 2002 .

[21]  M. Stiles,et al.  Model for exchange bias in polycrystalline ferromagnet-antiferromagnet bilayers , 1999 .

[22]  A. Sakuma,et al.  Influence of the spin structure for the exchange bias of antiferromagnetic and ferromagnetic bilayer , 2003, Digest of INTERMAG 2003. International Magnetics Conference (Cat. No.03CH37401).

[23]  W. D. Doyle,et al.  FeTaN/IrMn exchange-coupled multilayer films as soft underlayers for perpendicular media , 2001 .

[24]  R. M. Wolf,et al.  Exchange biasing in MBE grown Fe3O4/CoO bilayers: The antiferromagnetic layer thickness dependence , 1996 .

[25]  Kentaro Takano,et al.  Exchange anisotropy — a review , 1999 .