Field Gradient Induced by Organic Intercalation of Superconducting Layered Dichalcogenides

Magnetic-resonance observations of niobium nuclei in both the layered dichalcogenide NbS₂ and the associated intercalation complex NbS₂ (pyridine)1/2 yield different electric field gradients in the two compounds. At 4.2^∘{}K, e²qQh=60 MHz in NbS₂ and 46 MHz in NbS₂ (Py)1/2. The difference is shown to arise from the conduction-electron term. It may result from charge transfer between the organic molecules and the conduction band of the layered dichalcogenide, or from redistribution of electrons between two overlapping conduction bands. The lattice sum for the field gradient is shown to be derived almost entirely from intralayer charges.