Radio‐Frequency Size Effects in Cadmium in Magnetic Fields Inclined to the Sample Surface

The r.f. size effect is investigated in cadmium, for different field slopes relative to the surface, using a frequency of 5 MHz and magnetic fields up to 10⁴ Oe. When the angle between H and the basic plane of the “lens‐shaped” Fermi surface of the third band is less than 32°, some sections are found with the extremal value of \documentclass{article}\pagestyle{empty}$ \left({\frac{{\partial S}}{{\partial K_H }}} \right) $ , giving the size effect along spiral paths. For H ⊥ [0001] these sections involve K_H = 0.41 Å⁻¹ with \documentclass{article}\pagestyle{empty}$ \left({\frac{{\partial S}}{{\partial K_H }}} \right)_{ext} $ = (1.112 ± 0.03) Å⁻. By changing the field slope angles from zero to 90°, and rotating H in the basic plane, it is possible to observe the change in character of the impedance oscillations on the spiral paths. For slope angles between 7° and 17° the size effect lines at the spherical support point of the „lens”︁ are also observed. This gives the radius of curvature as (1.32 ± 0.1) Å⁻¹.