EPR Studies of the Near-Surface Layer in a Dilute Gold-Erbium Alloy

Annealing a foil of a dilute Au: Er alloy at 400 C produced a near-surface layer approximately 0.5 μm thick, with properties different from those of the bulk. These results were obtained using the electron-paramagnetic-resonance (EPR) technique. A theory for the EPR line shape was developed which showed that the $\frac{A}{B}$ ratio of a paramagnetic impurity in a metal can vary when a near-surface layer exists. The theoretical results may explain anomalous $\frac{A}{B}$ ratios observed in EPR experiments on other dilute metal alloys.