Mass Fluctuation Waves

Abstract

The motion of a ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particle through a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ lattice leads to an excitation (a mass fluctuation wave) which strongly couples to the phonons and provides a simple explanation for the NMR data in solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ mixtures.