The present state of understanding of the dynamics of magnetic domain walls and magnetic bubbles is reviewed. The theory of domain wall motion for the linear and non-linear regions is outlined. Experimental techniques for straight walls and magnetic bubbles are discussed. An extensive comparison between theory and experiment is made. Topics included are peak and saturation velocities, mobility, inertial effects and overshoot, hard bubbles, wall states and state transformations in magnetic bubbles. Origins of wall damping are also discussed.

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The molecular-beam electric resonance method served to measure the radio-frequency spectra of NaCl and to determine the hyperfine constants and the dipole moments for the '/)=0, 1, 2, and 3 vibrational levels of Na 35 Cl, and for the '/)=0 and 1 vibrational levels of Na 37 Cl.

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It is necessary to use this form of the rate equations which involves the negative, rather than those which involve the positive exponentials [Eqs. (13) and (14) of Ref. 4J to avoid roundoff errors in the sums which would eliminate all significant figures. The averaged populations used in Eq. (0 are calculated by n=![n(±to) +exp( -=to) ·n(±to) J. (A6)In calculations for the intermediate-and high-pressure regions, the approximation can be used that nCO) =n8q THE JOURNAL OF CHEMICAL PHYSICS andn(±to) =n P , wherenPis the steady-state population with the pumping power on. This approximation speeds up the calculation greatly, as it eliminates the calculation of exp( -=-5=)t o and the solving of the homogeneous set of equations (AS). In the low-pressure region, the program calculates the complex relative amplitude both exactly and with this approximation. As the pressure is increased, the two results agree to within better than experimental error, and only the approximate calculation is carried out for subsequent higher pressures. This approximation has proved to be accurate down to 10 p..Copies of this program, on cards, together with instructions for its use and sample input data are available from the authors.The molecular-beam electric-resonance method has been used to observe the radio-frequency spectra of 39K79Br and 39~81Br ~n the J = 1 rotational state and the 11=0, 1, and 2 vibrational levels. Analysis of the spectra has given dipole moments and hyperfine interaction constants of these molecules.

We report the observation of damped oscillations of a single straight magnetic domain wall stabilized by an externally applied field gradient in a Ga-YIG film (Y2.9La0.1Fe3.8Ga1.2O12). The measurements are performed at various field gradients, in-plane fields, and wall drive fields. We analyzed the results using the Landau-Lifshitz-Slonczewski (LLS) theory and obtained the wall width parameter Δ≡ (A/Ku)1/2 = (0.89±0.15) ×10−5 cm and the corresponding wall mass m0≡ (2πγ2Δ)−1= (5.2±0.9) ×10−11 g cm−2, where A is the exchange constant, Ku is the uniaxial anisotropy constant, and γ is the gyromagnetic ratio of the material; the Gilbert damping constant α=0.005±0.001; and the reduced Landau-Lifshitz damping constant λ/γ2= (1.3±0.3) ×10−9 Oe2 s. The wall mass according to Döring as calculated from γ, A, and Ku is m0=[2πγ2(A/Ku)1/2]−1= (8.1±0.6) ×10−11 g cm−2 and is higher than the experimental value. The observed oscillations allowed an independent determination of the magnetization of the material (4.2±0.8 G) in agreement with a direct measurement (4.8±0.5 G). In an applied in-plane field of 262 Oe the peak velocity was 530 m s−1. This value is lower by a factor of 1.6 compared to the peak velocity predicted from the LLS theory. From an observed asymmetry in the dependence of the wall oscillation frequency on the applied in-plane field we deduced that at the domain wall an effective in-plane field of 23±6 Oe is present, which is in the direction of the stray field at the film-air interface. A model of a film having two layers is proposed to explain this field. At a low in-plane field we observed a wall oscillation with a low frequency, depending on the drive field amplitude. It is not excluded that this slow oscillation is due to a wall containing Bloch lines.

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The dynamical behavior of straight magnetic domain walls and propagating magnetic bubbles in single-, double-, and triple-layer lanthanum gallium garnet films is reported. In the study of straight walls in the single-layer films, a good agreement is obtained between the observed and the calculated values of the domain-wall width parameter Δ, the derivative of the peak velocity to in-plane field at high in-plane fields, and the derivative of the saturation velocity to in-plane field at a moderate drive field and high in-plane fields H1. The saturation velocity (at H1=0) decreases with decreasing film thickness, which is in disagreement with theoretical predictions. A propagating bubble in a single-layer film exhibits an overshoot. In double- and triple-layer films, the observed and calculated Δ values disagree in most cases, and the straight wall and propagating bubble saturation velocities are significantly higher than in single-layer films. Overshoots and low-frequency oscillations are observed in the saturation regime of straight walls. The resulting high wall masses are attributed to stacking of horizontal Bloch lines on the film surface(s). From the measurements in in-plane fields, we conclude that the saturation velocity and the peak velocity in a double- and a triple-layer film depend on the polarity of the in-plane field, which is always perpendicular to the straight wall. It is found that the saturation region in double- and triple-layer films can be subdivided in three parts. This is explained qualitatively, and a calculation is made of the saturation velocity in double- and triple-layer films. This calculation shows good agreement with experimental results.