Ballistic-type field penetration into metals illustrated by high- and low-frequency size-effect measurements in silver

Radio-frequency size-effect experiments were performed on silver plane-parallel plates at high, 45 GHz, and low, 3 MHz, frequencies. By investigation of size-effect structures we show the influence of frequency on the field distribution inside the metal. When the frequency increases, the splash structure of the field is eliminated because it takes a finite time for an electron to pass the effective region of the trajectory when compared to the time variation of the applied field. Hence only the field between the splash positions remains. The role of different types of trajectories under these conditions are discussed on the basis of Pippard's ineffectiveness concept. The Fermi velocities along the belly orbit (B→∥[001]) in silver are extracted from the high-frequency spectra.