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Epitaxial films of Ni, Co, and Fe of thickness (10 -500 A) have been studied on Cu(100) seed layers grown at room temperature on Si(100) substrates freshly etched in a hydrofluoric acid solution. X-ray diffraction and reflection high-energy electron-diffraction measurements confirm the epitaxial growth of Ni and Co on Cu(100) with a fcc(100) structure, whereas Fe grows with a bcc(110) Pitsch orientation relationship. Ferromagnetic-resonance measurements have been used to study the in-plane and out-ofplane magnetic anisotropies of these films. Experimental data were fitted by using energy-density expressions that include uniaxial perpendicular anisotropy and bulk cubic anisotropy terms. Ni films with 0 thicknesses (100 A show strong perpendicular magnetic anisotropy, which is attributed to a tetragonal deformation of the Ni lattice.

Phys. Rev. Letters JL8, 283 (1967). 5 F. J. Dyson, Phys. Rev. 98, 349 (1955). 6 M. Lampe and P. M. Platzman, Phys. Rev. 150, 340 (1966). 7 In principle, an absolute measurement of the susceptibility determines the value of the isotropic exchange parameter. In practice, this measurement [R. Schumacher, T. Carver, and C. P. Slichter, Phys. Rev. 95^, 1089 (1954)] is extremely difficult to perform and gives results which necessarily have poor accuracy. 8 P. Nozieres, Theory of Interacting Fermi Systems (W. A. Benjamin, Inc., New York, 1964). 9 The mass m* is the effective quasiparticle mass which includes band-structure effects, phonons, and Using the ac Josephson effect, we have determined that 2e/h = 483.5912 ±0.0030 MHz/jxV. The implications of this measurement for quantum electrodynamics are discussed as well as its effect on our knowledge of the fundamental physical constants.

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We report the observation of electron spin resonance (ESR) in ferromagnetic Sc3+xIn. This material shows a strong narrow peak in the total magnetization as a function of x, with ferromagnetism occurring at low temperatures for x in the range of 0.10–0.20. We have studied the ESR properties of thin polycrystalline plates for several values of x lying both within and also outside the ferromagnetic region. Measurements were made at 12 and 18 GHz as a function of temperature. The temperature range extended from 1.3 to 50 K (several times the maximum Curie temperature, Tc, of 7 K). The g-value (corrected for demagnetization effects) is 2.02±0.01 at 1.4 K and appears to decrease to approximately 1.99 at the highest observable temperatures. The minimum linewidth occurs at Tc and increases slightly at lower temperatures. For T>Tc the line broadens rapidly with increasing temperatures. A comparison of the ESR linewidth with the reciprocal of the total magnetization as a function of temperature shows that even though both have the same qualitative type of behavior, the quantitative agreement is not as good as that predicted by the theory of exchange enhancement of spin lifetimes. Although one might normally expect a rather fast relaxation rate for the electrons of such an alloy, it appears that the small g-shift and a form of exchange enhancement are important for substantially increasing spin lifetimes and producing narrow lines at low temperatures.