Thermal transport properties in aluminum crystals at liquid-helium temperature

The orientation and magnetic-field dependence of the thermoelectric power and Ettingshausen-Nernst effect at liquid-helium temperatures in transverse magnetic fields up to about 50 kG, have been investigated in different single crystals of aluminum with the heat current in the [100], [110], [111], and [112] directions. The rotation diagram of the thermopower show anisotropies which agree with magnetoresistance measurements. On these anisotropies are superimposed the same characteristic peaks which appear in the magnetoresistance. These peaks are attributed to magnetic breakdown. The field dependence of the thermopower and of the Ettingshausen-Nernst voltage show large-amplitude sinusoidal oscillations when the magnetic field $\overrightarrow{H}$ is parallel to the [001] direction. The oscillations are periodic in $\frac{1}{H}$ and are due to networks of open and closed orbits extending over second- and third-zone Fermi-surface sheets.