Journal of Magnetism and Magnetic Materials 278 (2004) 317–322 Temperature dependence of the linewidth of spin-waves in Co/CoO bilayers H. Moradi* Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad 917751436, Iran Received 6 September 2003; received in revised form 3 December 2003 Abstract Broadening of spin-wave modes in the ferromagnetic thin layer with temperature is investigated within the Born approximation in a coupled ferromagnetic/anti-ferromagnetic bilayer. The Damon–Eschbach mode is used as a model to calculate the frequency of spin-waves in the ferromagnetic layer. Exchange bias by interface coupling and a random magnetic field due to inhomgeneities of the interface are represented by an effective field. Within this model we can explain the observed broadening of spin wave modes with temperature. r 2004 Elsevier B.V. All rights reserved. PACS: 78.35+c; 76.50+g; 75.70 cn; 75.50 Lk; 72.25.Rb Keywords: Linewidth; Co/CoO; Ferromagnetic/antiferromagnetic; Born approximation; Spin waves Exchange coupling was first observed in partially oxidized ferromagnetic thin layer (Co) fine particles in 1956 [1]. This effect induces a shift of the hysteresis loop away from its original location and is due to exchange coupling between ferromagnet (FM) and antiferromagnet (AF) layers based on the assumption of coupling across the interface [2]. Theoretically, there have been two typical models, the first model assumed that the FM was uniformly coupled to one sublattice of the AF, but simple calculations within this model gave interfacial exchange energies much larger than the experimental values. The other model, proposed by Malozemoff, considers the FM/AF interface to be imperfect with the existence of random exchange interactions between the FM and AF spins [2]. This model predicts a shift of the hysteresis loop that is consistent with experiment. Experimentally, there has been much work to relate the interlayer exchange coupling to hysteresis loop measurements [3,4]. Recently, Brillouin light scattering (BLS) as a powerful technique is used to study the properties of magnetic thin films [5,6]. This technique gives the frequencies of spin-waves, which depend on the effective field. Within this technique, the linewidths of long-wavelength spin-waves of Fe films coupled ARTICLE IN PRESS *Tel.: +98-511-861-4038; fax: +98-511-843-8032. E-mail address: moradi@ferdowsi.um.ac.ir (H. Moradi). 0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.04.103