1 Phys. IV France 8 (1 998.) Pr2-327 Static and dynamic properties of ferromagnetic thin films with stripe domain structure D. Pain, 0. Acher, D. Damiani, C. Boscher, N. Vukadinovic* and H. Niedoba** DMAT/CF/MMH, CEA Le Ripault, BP. 16, 37260 Monfs, France * Dassault Aviation, 92552 Saint-Cloud cedex, France ** CNRS, Laboratoire de Magnefisme et dJOptique de Versailles, 78035 Versailles cedex, France Abstract. We investigate the properties of ferromagnetic films deposited by magnetron sputtering, with a stripe domain structure. The domain structure is visualized by Kerr microscopy. We propose a model based on the minimization of a free energy of the stripe system, which allows us to fit the complete hysteresis curve. We can deduce the domain period and the magnetic parameters from the experimental hysteresis curve. We obtain a reasonable agreemen[ on the stripe width with our observations, and with previous works. The dynamic response in the 10 MHz to 3 GHz range is also studied. The resonance frequencies are computed by the Smit and Beljers method. The calculated resonance frequencies are in good agreement with our observations. 1. INTRODUCTION Ex~ensive studies have been performed on ferromagnetic domain structures. We investigate the stripe structures. Recently. it has been reported that films with stripe domains exhibit a very peculiar dynamic behaviour [I]. We extended these observations in the 10 MHz to 6 GHz and proposed a model to account for this behaviour [2]. In the present work, we use this model to account for the hysteresis curve and to deduce the magnetic anisotropies and stripe width from the experimentally observed hysteresis loop. The resonance frequencies can be computed from these parameters, and compared to experimental results. 2. EXPERIMENTAL DETAILS AND RESULTS Thin CoFeNiMoSiB films were deposited on kapton using magnetron sputtering [3]. Under high deposition power conditions, the films exhibit hysteresis loops typical of films with biaxial anisotropy. Their saturation magnetization is measured to be close to 7700 Gauss. The films exhibit rotatable anisotropy, that is the in-plane magnetization can be orientated by a proper field in any direction of the film plane. This is generally associated with the stripe structure. The domain structure has been investigated using the high resolution Kerr effect with digital contrast enhancement. For all studied samples, stripe domain patterns were observed both in an ac-demagnetized and remanent state. a) b) Figure 1 : Structure observed by Kerr effect on a 0.54 pm a) and on a 1 pm b) CoFeNiMoSiB layer ferromagnetic film Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jp4:1998276