Dielectric anomaly at the metal-insulator transition as seen by electron spin resonance 1. Analysis of the ESR line shape for poor conductors

Abstract

The shape of the electron spin resonance (ESR) line for itinerant electrons is asymmetric. The asymmetry is due to a microwave phase shift inside the sample. A complete equation for the power absorbed in conducting media is derived in this paper; it includes spin diffusion, sample size and displacement-current effects. This new formalism is appropriate to study the ESR of heavily doped semiconductors. It is shown that ESR may be a powerful technique to measure the dielectric constant in these media. An application to the study of the dielectric anomaly in lithium-ammonia solutions is given in Part 2 of this paper.