NMR search for charge density waves

Abstract

We show that the presence of a static charge density wave (CDW) should have pronounced effects on the NMR spectrum of a metal, such as potassium. With a thermally fluctuating CDW, the effects are averaged out, but may leave a residual contribution to the linewidth. Observed NMR spectra in potassium metal rule out the presence of a static CDW, but do not rule out the existence of a thermally fluctuating CDW. Our linewidth data combined with spin-lattice relaxation data of others require that the axis of the charge density wave be parallel to the applied field and that thermal fluctuations be rapid enough to produce correlation times less than 1.3 × ${10}^{-7\mathrm{}}$ sec at 1.5 K. We are able to account for our linewidth (0.215 ± 0.015 G) with interactions characteristic of the uniform-density conduction-electron state.