Momentum space structure of quasielastic spin fluctuations in Ce$_{3}$Pd$_{20}$Si$_{6}$

Ce$_{3}$Pd$_{20}$Si$_{6}$ is one of the heaviest electron systems amongst the heavy-Fermion metals. We have used high-resolution neutron spectroscopy to observe the low-energy region of magnetic scattering from the paramagnetic state, finding that at low temperatures the quasielastic magnetic response is present throughout the Brillouin zone. It forms a broad hump, centred at the (111) scattering vector, surrounded by minima of intensity at (002), (220) and the equivalent wavevectors. This momentum space structure distinguishes it from a simple crystal-field excitation, as proposed previously, and suggests it results from short-range dynamical correlations between the Ce ions, mediated by itinerant \textit{f}-electrons via the RKKY interaction. The momentum-space symmetry of the quasielastic response suggests that it stems from the cubic Ce sub-lattice occupying the 8c Wyckoff site, which is responsible for hosting static AFM order below $T_{\mathrm{N}}$, in contrast to the crystallographically inequivalent 4a site which does not appear to contribute magnetically.