Observation of the conduction-electron spin resonance from metallic antimony-doped silicon

Electron spin resonance has not previously been detected for barely metallic Sb-doped silicon. We report preliminary measurements at 9.4 GHz in the temperature range 1.4<T<4.2 K for two Sb-doped silicon samples with concentrations close to the critical density n(c) for the metal-insulator transition. The peak-to-peak linewidths were 21 and 45 Oe for the samples at n(c) and 1.28n(c), respectively. The results support Pifer's assertion that the conduction-electron spin resonance linewidth is determined by the impurity spin-orbit interaction.