Magnetothermal Oscillations. The Oscillatory Dependence of Temperature on Magnetic Field

Abstract

Magnetothermal oscillations are a new low-temperature phenomenon. They result from quantum effects and can be employed as a useful tool for exploring the electronic band structure of metals. Magnetothermal oscillations show up experimentally as a reversible and cyclic variation of the temperature of a thermally isolated single crystal, such as bismuth, as either the magnitude or the direction of an externally applied magnetic field is changed in a uniform manner. The oscillatory temperature changes are periodic in $\frac{1}{H}$, and their variation with orientation is dependent on the detailed shape of the pertinent part of the Fermi surface in much the same manner as magnetic susceptibility oscillations. Of the oscillatory effects used for the study of Fermi surface shapes at moderate magnetic fields, magnetothermal oscillations have yielded the best resolution in bismuth. The high resolution obtained in the magnetothermal experiments made it possible to observe for the first time fine structure in de Haas-van Alphen oscillations due to electron spin. Data for bismuth, showing magnetothermal oscillations as a function of magnetic field strength or the field direction, are presented and discussed.