Dynamical properties of quasiparticle excitations in potassium and rubidium

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Abstract
De Haas-van Alphen effect measurements have been made of the cyclotron effective masses for a large number of orbits over the Fermi surfaces of potassium and rubidium. Problems of measurement that arise in the pure metals from magnetic interaction and finite skin depth effects were avoided by working with dilute alloys of K(Na) and Rb(K). For potassium the authors find m*/m0=1.230+or-0.013 with no evidence of anisotropy, but for rubidium they observe an anisotropy of 3.1% and a mean value of m*/m0=1.260+or-0.001. The variation of electron quasiparticle velocity over the Fermi surface has been computed from a cubic harmonic representation of the experimental data. These experimental results lend support to calculations by Leavens and Carbotte (1973) of the anisotropic electron-phonon renormalisation and permit the magnitude of the electron-electron renormalisation in these metals to be estimated.