Cyclotron-wave transmission in sodium and potassium at 80 GHz

Abstract

A comprehensive study of cyclotron waves is reported for sodium and potassium. Using a sensitive microwave-transmission spectrometer operating at 80 GHz the authors observe cyclotron waves for which, at low temperatures, the product omega tau (frequency multiplied by the scattering time) is so high (100-150) that direct comparisons of the theoretical dispersion curves with measured data are readily accomplished. From such comparisons they have determined accurate values for the many-body parameters A2 and A3 for both metal together with estimates for the higher order parameters A4 and A5 for potassium. Using the most accurate values of m*/m0 available (1.211 for K and 1.256 for Na) they find A2(K)=-0.0283+or-0.004 and A2(Na)=-0.0253+or-0.0024, while A3(K)=0.0007+or-0.005 and A3(Na)=0.008+or-0.004, the other higher order Ans being effectively zero. These results compare favourably with other less precise determinations as well as theoretical predictions. Also, by combining A2, A3 and the spin-dependent Fermi-liquid parameters (determined from the spin-wave modes) with an appropriate sum rule, they have estimated the addition parameter A1, for both sodium and potassium.