Strong anisotropy of the electron-phonon interaction in NbP probed by magnetoacoustic quantum oscillations

Abstract

In this study, we report on the observation of de Haas--van Alphen--type quantum oscillations (QOs) in the ultrasound velocity of NbP as well as ``giant QOs'' in the ultrasound attenuation in pulsed magnetic fields. The difference in the QO amplitude for different acoustic modes reveals a strong anisotropy of the effective deformation potential, which we estimate to be as high as $9\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ for certain parts of the Fermi surface. Furthermore, the natural filtering of QO frequencies and the tracing of the individual Landau levels to the quantum limit allows for a more detailed investigation of the Fermi surface of NbP, as was previously achieved by means of analyzing QOs observed in magnetization or electrical resistivity.