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

Phys. Rev. B 49, 3283–3293 (1994)

[Issue 5 – 1 February 1994 ]

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Spin-wave study of the magnetic excitations in sandwich structures coupled by bilinear and biquadratic interlayer exchange

Monica Macciò and Maria Gloria Pini

Istituto di Elettronica Quantistica, Consiglio Nazionale delle Ricerche, I-50127 Firenze, Italy

Paolo Politi and Angelo Rettori

Dipartimento di Fisica, Universitá di Firenze, I-50125 Firenze, Italy

Using a microscopic and quantum approach, we study the ground-state configuration and the spin-wave excitations of a model of two ferromagnetic monolayers, interacting via both bilinear and biquadratic exchange, and subject to an easy-plane anisotropy, a quartic in-plane anisotropy and an external field. In the framework of a Green's-function method, we obtain analytical results for the spin-wave dispersion curves. Peculiar features are found in the field dependence of the acoustic and optical frequency gaps, in correspondence to the critical fields for which the canting angle between the magnetizations of the two coupled layers presents discontinuities. In particular, a minimum for the optical gap at the saturation field is predicted, which could be experimentally observed by Brillouin light scattering in real systems.

©1994 The American Physical Society

URL: http://link.aps.org/abstract/PRB/v49/p3283
DOI: 10.1103/PhysRevB.49.3283
PACS: 75.30.Ds, 75.50.Rr, 75.70.Cn

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