After a short introduction to NMR technique, a brief, three-part survey of recent NMR studies on solid-state materials will be presented. These studies are each underpinned by an exact theoretical result that leads to a possibly approximate, but reliable basis for interpretation of experimental data. The first example is the behavior of nuclear spin-lattice relaxation in two of the high-Tc materials vis-a-vis inelastic neutron scattering (INS) studies that evaluate the dynamic susceptibility chi”(q,omega). Such a comparison shows that a substantial amount of intensity for chi” is simply missing from currently available INS data. The other two examples feature NMR studies of the stoichiometric QCP compound YbRh2Si2. In the first of these, NMR shows that high-quality crystals of this system enter into a macroscopic two-state admixture of non-Fermi-liquid and Fermi-liquid phases. Such a result is not accessible with bulk measurements. In the second example, quantitative measurements of indirect spin-spin couplings exhibit a temperature dependence revealing modifications of the Fermi Surface with temperature. To our knowledge, none of the results described has any precedent in the NMR literature.

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