The physics underlying the propagation and attenuation of acoustic waves in ferromagnetic metals is discussed. The propagating modes are considered as coupled acoustic phonon-magnon-photon modes and their dispersion relation is derived for both ferromagnetic insulators and metals by treating the modes as electromagnetic waves. The damping of the coupled modes is discussed in terms of the individual damping mechanisms for the acoustic phonons, magnons and photons and their relative content as a function of frequency. Data on the attenuation of high frequency (220 MHz) sound waves at low temperatures in ferromagnetic Ni is presented and discussed.

We report the results of an investigation of the magneto-quantum-electric effect associated with the absorption of phonons or photons by charge carriers (electrons or holes) in solid state plasmas in the presence of a static magnetic field H0. The effect is based on the lateral displacement (in a direction perpendicular to both q and H0) of the centers of the cyclotron orbits of the charge carriers upon absorption of quanta with a component of wave vector q in the plane of the real-space orbits. Simple theoretical arguments are used to show that: (a) for spherical energy surfaces, this displacement occurs for q Ho when quanta are absorbed in cyclotron (Δn=±1) transitions, and (b) for ellipsoidal energy surfaces, the absorption of quanta leads to a displacement which is perpendicular to q and to the normal to the plane of the orbit in either cyclotron (Δn=±1) or Landau (Δn=0) transitions. In both cases, the lateral translation due to continuous quanta absorption constitutes a ‘d.c.’ current. This current sets up a surface charge density on the lateral boundaries of the sample, and thus, a d.c. electric field appears across the sample. A comparison is made of the MQE effect with several similar and/or related effects. The MQE fields associated with the giant-quantum-absorption of longitudinal phonons in bismuth are observed and are shown to be in excellent agreement with the predictions of the theory.

Liquid-helium-temperature tunneling data for PbTe indium-doped $p\ensuremath{-}n$ junctions exhibit a series of sharp conductance increments with \ensuremath{\sim}5-mV spacing as well as the "zero-bias conductance minimum" and the LO-phonon shoulder at \ensuremath{\sim}13.8 mV. Indium-gallium alloyed junctions exhibit also a second series with \ensuremath{\sim}6.5-mV spacing. This periodic structure is attributed to the "inelastic scattering" of tunneling electrons by localized vibrational modes of the indium and gallium impurity atoms in the tunneling junction.

We propose a new phenomenon, the "Magneto-Quantum-Electric Effect," based on the lateral displacement of the centers of the cyclotron orbits of the carriers when the momenta transferred to the carriers from phonons or photons have components in the plane of the orbits in real space. We discuss the magnitude of the effect for a compensated and an uncompensated plasma, and also its effect on the absorption constant of phonons or photons.

The tunneling spectra on Bi2Sr2CaCu2O8 single crystals have been investigated in magnetic fields up to 20 T by using the break-junction technique. The second derivatives d2I/dV2(V) exhibited additional symmetrical structures at voltages above the energy gap. These structures were broadened in magnetic fields together with the gap structure, but remained at 20 T. The data were inverted by using the Rowell—McMillan program in order to obtain the α2F(ω) function for the electron—phonon interaction. The main features of α2F(ω) are well reproduced for different samples and can be reasonably compared with the phonon density of states obtained by inelastic neutron scattering.

We report the observation of magneto-quantum-electric fields associated with the giant-quantum attenuation of sound waves in bismuth. For suitable orientations of $\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}$ and ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}$, a set of voltage peaks appears, whose magnetic-field dependence and the magnitudes are in good agreement with theory. Voltage peaks also appear in a direction corresponding to transverse electric fields set up by the longitudinal acoustoelectric current and the anisotropic resistivity of bismuth.