Quadrupolar magnetically induced nuclear interaction

The most common interactions are dipolar coupling between two spins, chemical shielding and quadrupolar interaction for spins I> 1. The chemical-shielding interaction arises from the motion of electrons around a nucleus induced by the external applied static magnetic field. This motion generates local magnetic fields that modify the total field experienced by the nucleus, and are characteristic of the local chemical environment of the nuclei. All nuclei with a spin /> 1 possess a quadrupolar moment Q that interacts with the EFG Vrs — d2 V/dXfdx at the nuclear site. The EFG tensor Vrs is a symmetric tensor with zero trace Tr( E) = A E = 0 (from Laplace equation). 

The magnetically induced electric quadrupolar interaction was recently observed in several cubic, ferromagnetically ordered intermetallic compounds at the nucleus of the rare-earth S-state ions Gd and Eu, despite the fact that the nuclei are residing on nominally cubic lattice sites e.g., nuclear quadrupole... 

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