Extreme conduction electron spin resonance: A/B→(5+33)/4, the universal limit of lineshape asymmetry ratio

Abstract

We derive the Electron Spin Resonance (ESR) lineshape in conducting crystals, relying on the density matrix description. In our approach, lineshape is determined as linear combination of absorptive and dispersive signals with non-negatively real coefficients, corresponding to the NMR limit. The significant points and segments of the total signal at resonance have been systematically quantified, and along that line, we have formulated an alternative fitting strategy consisting of few straightforward steps to obtain the relevant ESR parameters in metallic systems. Finally, by examining different crystal geometries, the universal value, A/B→(5+33)/4, of the lineshape asymmetry ratio has been derived in the case of metallic particles with extreme conductivity.