In recent years a number of papers have considered the appearance of objects moving at relativistic speeds as seen by a single observer. This paper explores the stereoscopic effects of using a pair of eyes or observing instruments, assuming that the light rays from the object arrive simultaneously at the two eyes and that the instantaneous apparent position of a point object is the intersection of the lines of sight of the two eyes. Contrary to what is true for objects at rest, stereoscopic observation of moving objects does not determine correctly either their shape or position.
so that the conductivity o(oo) can be expressed as aM = a(0)/[l+uoT(a>)](6) 1/T(U)) is found to be of the form of Eq. (4) with T'^O)) given approximately by r ml (u))^\B(Hu)/nk) 2~0 .94xiO 10 sec" 1 (7)at 891 GHz . The observed enhancement of the relaxation rate at 891 GHz (with consideration of nonlocal effects) is about 60% greater than predicted by Eq. (7). The significance of the discrepancy is questionable because of the crudeness of the model calculation. However, such a deviation is of interest as it would suggest a phonon-mediated (BCS) electron-electron coupling in which A fe is energy dependent. The authors thank R. E. Prange, J. F. Koch, and S. M. Bhagat for many helpful discussions, as well as Scott Brownstein and Clyde Bradley for valuable assistance in the laser design and construction. 1 P. Goy and G. Weisbuch, Phys. Rev. Lett. £5, 225 (1970). 2 V. S. Edel'man and S. M. Cheremisin, Pis'ma Zh.A distinctive and strong microwave magnetic transmission resonance mode is reported in ferromagnetic Gd, Fe, and Ni when the static magnetic field is parallel both to the sample foil surface and to the microwave magnetic field. Some evidence exists to show that this may involve sensitive detection of two-magnon processes as in parallel pumping.
A theory of the ferromagnetic transmission resonance is presented for the case where the static magnetic field is perpendicular to the sample surface. The theory is compared with experiments performed on ferromagnetic gadolinium and nickel. The agreement between theory and experiment is satisfactory. Since the transmission resonance is a bulk effect it will allow the study of the bulk spin relaxation time and exchange integral as functions of temperature.Following the observation, 1 identification, 213 and accurate description 4 of magnetic transmission resonance in Gd, due to microwave skindepth modulation (enhancement) under resonance conditions, similar transmission signals were observed in ferromagnetic Gd, 4 Fe, Ni, Co and Connetic AA. 5 The Gd samples were 60 j^m thick and 99.9% pure. The Fe, Ni, Co samples were about 10 jbtm thick and of much higher purities. The Connetic AA samples had intermediate thicknesses. The experiments were done at a frequency of 9.2 GHz. The apparatus was similar to that used for spin transmission experiments in Pauli paramagnetic metals 6 and utilized a pair of cavities, which when assembled have their E fields crossed at 90°. As in the case of paramagnetic Gd we have observed ferromagnetic transmission signals for the above metals in two geometries: the static magnetic field being either parallel or perpendicular to the sample surface. Since the transmission resonance effect is a bulk effect, it occurs for both geometries at the field B int = (jt) t f/y and for the perpendicular geometry appears at applied fields lower than the absorption resonance does. The transmission in paramagnetic Gd is described very accurately through the solution of the Maxwell and Bloch-Bloembergen 7 equations with boundary conditions and no consideration given to the waves reflected back to the bulk from the second surface of the sample.Attempts to describe the observed 4 ' 5 ferromagnetic transmission resonances through the same equations with an exchange term added to the magnetic field 8 * 9 and boundary conditions enforced on the magnetization 8 * 10 ' 11 failed originally. We have, however, recently realized that the waves reflected from the second sample face back to the bulk cannot be neglected in the ferromagnetic case, at least for the sample thicknesses we used, since the ferromagnetic magnetization is very large compared with the paramagnetic one. Following these ideas, we developed theories for both the perpendicular and parallel static-field geometries. In this paper we present the results for the first case in connection with Gd and Ni. The parallel case results are similar to the ones discussed below but more involved.The general equations of the problem areand H t , M t , are the transverse H and M fields, o is the conductivity of the metal, H is the applied static field, H int is the total field inside the metal, T is the transverse relaxation time, M is the saturation magnetization, and A is the exchange stiffness constant. In the following equations 6 is the skin depth given by 6 2...
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