De Haas-van Alphen effect in sodium under pressure

Abstract

A study of the de Haas-van Alphen (DHVA) effect in sodium under pressures of up to approximately 4 kbar has been made. The pressure derivative of the frequency (1/F0)dF/dP was found to be (0.76+or-0.02)*10-2 kbar-1, which is about 7% lower than that predicted from the compressibility data of Beecroft and Swenson (1961). The possible significance of this discrepancy is discussed, although it is just within the combined uncertainty of the measurements of the compressibility and DHVA frequency. Determination of the cyclotron effective mass yielded a zero pressure value of (1.256+or-0.002)mo and a pressure derivative (1/m*)dm*/dP of -(0.48+or-0.09)*10-2 kbar-1. This pressure dependence is explained in terms of changes in the band mass and electron-phonon mass enhancement. Dingle temperatures were in the range 0.3-1.5K, and depended on the number of temperature cycles of the sample. The DHVA oscillations were not observed after a few (3-7) temperature cycles, due to the sodium martensitic phase transformation.