Navegando por Autor "Stamps, R. L."
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Artigo Domain-wall resonance in exchange-coupled magnetic films(American Physical Society, 1997-03-01) Carriço, Artur da Silva; Stamps, R. L.; Wigen, P. E.Exchange coupling between magnetic films in multilayer geometries can strongly influence magnetization behavior and spin-wave energies by correlating the motion of spins in one film with the motion of spins in adjacent films. In a similar fashion correlations can be expected between domain walls existing in neighboring exchange coupled films. In this paper we show that the motion of domain walls in neighboring films can depend strongly on interfilm exchange coupling. A static equilibrium configuration exists for the domain walls, and small amplitude oscillations about equilibrium can result in domain-wall resonances that involve interfilm exchange energies. Frequencies for optic- and acoustic-type domain-wall resonances are calculated and effects of a small static applied magnetic field are examined, revealing distinctly different behaviors for the acoustic and optic domain-wall resonances. The possibility for sensitive measurements of the local coupling by studying domain-wall resonance is discussed. Resonances with parallel and antiparallel coupling are considered and the response to a small in-plane driving field is calculated.Artigo Exchange coupled domain walls: Resonance in multilayers(AIP Publishing LLC, 1997-04-15) Carriço, Artur da Silva; Stamps, R. L.; Wigen, P. E.Exchange coupling between magnetic films can lead to an attractive force between domain walls in the separate films. The coupling between the films allows for small amplitude oscillations around the equilibrium configuration of the walls, analogous to optic and acoustic type spin wave resonance modes. Since the restoring force acts only over the length of a domain wall, this suggests the possibility of sensitive measurements of the local coupling by studying domain wall resonances. The effects of applied fields are also examined. With antiferromagnetic coupling, small static fields push the walls apart and result in different behaviors of the acoustic and optic domain wall resonances.Artigo Finite-size effects on spin configurations in antiferromagnetically coupled multilayers(American Physical Society, 1992-11-01) Carriço, Artur da Silva; Camley, R. E.; Nörtemann, F. C.; Stamps, R. L.Nonuniform canting states are found for multilayers of a finite size that are constructed from ferromagnetic films which are antiferromagnetically coupled. Our results are applicable to a wide variety of experimentally realizable systems such as Fe/Cr and Co/Ru. We find that at low fields, a twist in the ground-state configuration of the spins reduces the net Zeeman energy and is energetically favorable to the uniform canted state which has previously been assumed by most authors. At higher fields, the character of this twist changes and eventually leads to a state that is fully aligned along the direction of the applied magnetic field. A numerical self-consistent mean-field model is used to examine the properties of these states and a variational method is developed in order to obtain analytic expressions for the lengths and magnitudes of these twists. The deviations from the uniform spin-flop state at both high and low fields can be quite large and involve the entire sample.Artigo Local modes of thin magnetic films(American Physical Society, 2000-10-01) Carriço, Artur da Silva; Dantas, Ana Lucia; Stamps, R. L.We calculate the frequency of rigid displacement domain wall excitations of a Nèel wall in a thin uniaxial ferromagnetic film. The domain wall is pinned by a line defect running along the uniaxial axis. We study the effect of an external field applied along the magnetization of one of the domains. The restoring force originates from energy fluctuations resulting from spin motion within the domain wall width and the excitation frequency turns zero when the external field approaches the threshold value for depinning the domain wall from the defect. The results are applied to the study of excitations of a Nèel wall in a thin uniaxial ferromagnetic film exchange coupled to a uniaxial two-sublattice antiferromagnetic substrate.Artigo Phase diagram of thin antiferromagnetic films in strong magnetic fields.(American Physical Society, 1994-11-01) Carriço, Artur da Silva; Camley, R. E.; Stamps, R. L.A theoretical study of the phase diagram of antiferromagnetic thin films is presented. The theory is based on a numerical self-consistent local-field calculation that allows for size and surface effects. The properties of magnetic structures as functions of the temperature and external field are calculated. Spatially nonuniform canted states are shown to intermediate the transition from the antiferromagnetic to the spin-flop phases. The model is applied to thin films of FeF2 and MnF2 as examples in order to clarify the role of anisotropy.