Magnetothermal Oscillations in Beryllium

Abstract

We were stimulated by the work of Kunzler et al. ¹ on bismuth to attempt to observe magnetothermal oscillations in a metal. Beryllium was chosen for this study because of its high Debye temperature (1150°K) and correspondingly low-lattice specific heat. The effect is associated with the oscillations in a magnetic field of the free energy of the conduction electrons; but since one measures changes in the lattice temperature due to an exchange of energy between the lattice and the electron system, the effect will be enhanced by a low lattice specific heat. Recently, we reported our first observations of magnetothermal oscillations in beryllium.² The amplitude of the oscillations was about 3 times that observed in a bismuth crystal under similar experimental conditions, even though the frequency was 8 times greater. Since then we have improved our experimental techniques and have observed frequencies from 10⁵ G to 1.5 × 10⁷ G. The measurements were made at 0.9°K in fields up to 21.5 kG. The maximum amplitude of the low-frequency oscillations was about 10^-2°K and of the highest frequency about 3 × 10^-5°K. The specimen was an 0.7-g single crystal of beryllium which was generously loaned to us by the Franklin Institute. ‡ Although we have not finished our study of the Fermi surface of beryllium, we would like to report here a brief description of the method and the principal results.

Supported by the National Science Foundation.

National Science Foundation Predoctoral Fellow.