Transmission electron spin resonance measurements of spin--flip scattering and crystal field parameters in dilute Al: rare earth alloys

Measurements were made on dilute alloys of Lu, Yb, and Dy in Al. The spin-flip cross section of the nonmagnetic Lu is 6.2 x 10-18 cm2, in approximate agreement with measurements on other rare earths in Al. Yb is also found to be nonmagnetic, but with a spin-flip cross section of 28 x 10-18 cm2, more than four times as large as the other rare earths. These data disagree with models of either divalent or trivalent Yb, indicating that Yb:Al may be an intermediate valence system. Dy is found to be magnetic, but the TESR g shift cannot be explained by the conventional J vector S.vector s exchange coupling model. A more complicated model, allowing for anisotropy of the exchange coupling, is used to interpret the data. Resistivity measurements as a function of concentration and temperature were made on Gd, Dy, Er, Tm, Yb, and Lu in Al. The residual resistivity is approximately constant at 3.5 μΩ-cm/at. percent. All the rare earths measured exhibit normal impurity resistivity, becoming temperature independent at low temperature