The magnetic response of irreversible type-II superconductor slabs subjected to in-plane rotating magnetic field is investigated by applying the circular, elliptic, extended-elliptic, and rectangular flux-line-cutting critical-state models. Specifically, the models have been applied to explain experiments on a PbBi rotating disk in a fixed magnetic field Ha, parallel to the flat surfaces. Here, we have exploited the equivalency of the experimental situation with that of a fixed disk under the action of a parallel magnetic field, rotating in the opposite sense. The effect of both the magnitude Ha of the applied magnetic field and its angle of rotation αs upon the magnetization of the superconductor sample is analyzed. When Ha is smaller than the penetration field HP , the magnetization components, parallel and perpendicular to Ha, oscillate with increasing the rotation angle. On the other hand, if the magnitude of the applied field, Ha, is larger than HP , both magnetization components become constant functions of αs at large rotation angles. The evolution of the magnetic induction profiles inside the superconductor is also studied.

The manifestation of flux-line cutting in the magnetic behavior of a type-II superconductor, either (i) subjected to a rotating magnetic field, or (ii) undergoing slow oscillations in a static magnetic field, is investigated theoretically. We have applied both the generalized double critical-state model and the two-velocity hydrodynamic one to interpret available experimental results for oscillating disks of Nb. The hydrodynamic model generates only closed hysteresis loops, after the first full oscillation, in accordance with the experimental hysteresis loops observed at a relatively small amplitude of oscillation, θmax=45°. However, at larger amplitudes of oscillation, several measured loops are evidently open. This behavior as well as their asymmetric form could be reproduced only by the generalized double critical-state model. The limits of applicability of both models are discussed.

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Electron and phonon transient temperatures are analyzed in the case of nondegenerate semiconductors. An analytical solution is obtained for rectangular laser pulse absorption. It is shown that thermal diffusion is the main energy relaxation mechanism in the phonon subsystem. The mechanism depends on the correlation between the sample length l and the electron cooling length l ⑀ in an electron subsystem. Energy relaxation occurs by means of the electron thermal diffusion in thin samples (lӶl ⑀ ), and by means of the electron-phonon energy interaction in thick samples (lӷl ⑀ ). Characteristic relaxation times are obtained for all the cases, and analysis of these times is made. Electron and phonon temperature distributions in short and long samples are qualitatively and quantitatively analyzed for different correlations between the laser pulse duration and characteristic times.

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