The isotropic magnetic interaction of a nuclear magnetic dipole moment with electron spin density at the atomic nucleus. A nonrelativistic penetrating orbital can have and a substantial contact contribution to hyperfine structure. A filled paired shell cancels its net contact spin density in the independent-particle approximation; unpaired occupation and core polarization can restore it. Relativistic and finite nuclear-size effects modify the point-contact description.
Articles by others on the same topic
The Fermi contact interaction is a type of interaction that occurs in quantum mechanics between two particles with nonzero spin when they are in close proximity. It arises from the exchange of virtual particles, which leads to an effective interaction that is sensitive to the spatial distribution of the spins of the particles involved. Specifically, the Fermi contact interaction is characterized by its dependence on the overlap of the wave functions of the interacting particles—typically their spins.