Signatures of electronic correlations and spin-susceptibility anisotropy in nuclear magnetic resonance

We present a methodology for probing the details of electronic susceptibility through minimally invasive nuclear magnetic resonance techniques. Specifically, we classify electron-mediated long-range interactions in an ensemble of nuclear spins by revealing their effect on simple spin echo experiments. We find that the pulse strength and applied field orientation dependence of these spin echo measurements resolves the spatial extent and anisotropy of electronic spin susceptibility. This Letter provides an alternate explanation to NMR results in superconducting and magnetically ordered systems. The methodology has direct applications for sensing and characterizing emergent electronic phases.