Spin-flop coupling and exchange anisotropy in ferromagnetic/antiferromagnetic bilayers

• Published in: Surface science 2009-03, Vol.603 (5), p.814-818
• Main Authors: Xu, Xiao-Yong, Hu, Jing-Guo
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Exchange anisotropy; FM/AF bilayers; Physics; Spin-flop coupling
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2009.01.031

By investigating the antiferromagnetic spin configuration, the exchange anisotropy and the interfacial spin-flop coupling in ferromagnetic/antiferromagnetic (FM/AF) bilayers have been discussed in detail. The results show that there are four possible cases for the AF spins, namely the reversible recovering case, irreversible half-rotating case, irreversible reversing and irreversible half-reversing cases. Moreover, the realization of the cases strongly depends on interface quadratic coupling, interface spin-flop (biquadratic) coupling and AF thickness. The magnetic phase diagram in terms of the AF thickness t AF, the interfacial bilinear coupling J 1 and the spin-flop coupling J 2 has been constructed. The corresponding critical parameters in which the exchange bias will occur or approach saturation have been also presented. Specially, the small spin-flop exchange coupling may result in an exchange bias without the interfacial bilinear exchange coupling. However, in general, the spin-flop exchange coupling can weaken or eliminate the exchange bias, but always enhances the coercivity greatly.