Electron paramagnetic resonance and relaxation of amorphous silicon below 1 K

Amorphous silicon, generated within crystalline Si by ²⁸Si⁺ ion implantation, exhibits an electron spin relaxation rate which varies with temperature as T^2.37 between 0.3 and 4.2 K. These results exclude the current model of a phonon-limited, direct relaxation mechanism in a-Si. A relaxation process, consistent with the known temperature variation, is outlined. EPR signal strengths, relative to a known paramagnet at temperatures near 1.2 and 0.4 K, put limits on an antiferromagnetic Curie-Weiss temperature of 0?θ?0.06 K.