Galvanomagnetic Properties of a Single-Crystal Sphere by the Induced-Torque Method. II. Magnetic Breakdown in Cadmium and Zinc

Experimental data from induced-torque measurements on cadmium and zinc for magnetic field directions perpendicular to the hexagonal axis are analyzed theoretically. In both Cd and Zn, magnetic breakdown between the first- and second-zone Fermi surfaces (the "caps" and the "monster") found by Datars and Cook is discussed. The change in topology, from open to closed orbits, makes the torque method an accurate tool for measuring the magnetic-breakdown parameters $B_0$; these are 8.8 kG (for Cd, $\overrightarrow{\mathrm{B}}$ parallel to [$10\overline{1}0$]), 18.7 kG (Cd; $\overrightarrow{\mathrm{B}}$ in [$11\overline{2}0$] direction), and 5.1 kG (Zn for $\overrightarrow{\mathrm{B}}$ along a direction in the basal plane 7° from [$10\overline{1}0$]). For Zn, a second magnetic-breakdown phenomenon has been found. This is between the first-zone "caps" and the third-zone "needles," and produces a transition between closed orbits and a different kind of open orbits. The breakdown parameter for this second effect is 38.5kG.