Mechanisms of nuclear acoustic resonance in conductors

A general analysis of the nuclear acoustic resonance mechanisms in conductors is given. It is shown that the independence of the observed line shape from the band structure comes from the simplicity of the mechanism of the Alpher-Rubin effect which is solely due to the Faraday induction law; this explains the success of crude electronic models. Furthermore, another coupling mechanism coming from transition metal paramagnetostriction is proposed. Finally, the apparently emitting character of the absorption shape is shown to be related to the need for spin renormalization to take into account the screening of the precession magnetic field by conduction electrons.