Giant Electron Spin-Resonance Transmission in Cu Ion Implanted with Mn

We observed for the first time the transmission of electron spin resonance through a thin copper foil implanted with Mn on either one or both sides at a dose of about ${10}^{15}$ ${\mathrm{i}\mathrm{o}\mathrm{n}/\mathrm{c}\mathrm{m}}^2$. We found an increase of intensity over that of the pure metal, at 1.5°K, by a factor of 50 for one-sided-implanted samples and 2500 for two-sided-implanted samples. This enhancement decreases with increasing temperature, while the $g$ factor remains very close to that of pure copper metal.