Nuclear magnetic resonance (NMR) is a spectroscopic technique in which the nuclei are used to probe matter at the atomic scale. NMR is a widespread tool used to image the human body (MRI), to perform chemical analyses or to resolve the structure of biomolecules. In condensed matter physics, we use NMR to elucidate the electronic and structural properties of solids.
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In a typical NMR experiment, a given nuclear species is spin-polarized by a static magnetic field and driven off-equilibrium by radiofrequency pulses. The radiofrequency response of the nuclei, recorded during the return back to equilibrium, measures how the environment of the nucleus affects the polarization. Analysis of this response provides us with a wealth of information about the local electronic, magnetic and structural properties, including how they possibly vary in space and how they fluctuate with time (dynamics).
The above example shows a two-component NMR resonance of 17O nuclei that provides evidence of charge-density wave formation in the high temperature cuprate superconductor YBa2Cu3Oy (more details here).