O. V. Kirichenko

Thermoelectric effect in layered conductors at low temperatures

The linear response of the electronic system of a layered conductor to the presence of a temperature gradient is investigated theoretically. The dependence of the thermoelectric power on the temperature and external magnetic field is found at temperatures below the Debye temperature. Experimental investigation of this dependence will make it possible to study different relaxation mechanisms in a system of conduction electrons and to determine the structure of the electronic energy spectrum.

Quantum oscillations of the thermomagnetic coefficients of layered conductors in a strong magnetic field

The linear response of the electronic system of a conductor to a perturbation in the form of an electric field and a temperature gradient in a quantizing magnetic field B is investigated theoretically. The thermoelectric effect in a layered conductor is analyzed and it is shown that the quasi-two-dimensional character of the dispersion law of the charge carriers results in gigantic oscillations of the thermo-emf.

Collective modes in quasi-two-dimensional conductors under strong spatial dispersion

Propagation of electromagnetic and spin waves in layered conductors with a quasi-two-dimensional dispersion law of charge carriers is investigated theoretically in the presence of an external magnetic field with induction B0. In layered conductors, the drift velocity vD of electrons along B0 is an oscillatory function of the angle between the magnetic field direction and the normal to the layers. For certain orientations of the magnetic field with respect to the layers of the conductor, vD is close to zero. In these directions, there is no collision-free absorption, and weakly damped waves may propagate even under strong spatial dispersion. In the short-wave-length limit, there may exist collective modes with frequencies in the neighborhood of resonances for arbitrary orientation of the wavevector k relative to B0. Similar types of excitations in quasi-isotropic metals are possible only when k is perpendicular to the direction of the external magnetic field.

Thermomagnetic phenomena in layered conductors

A theoretical study is made of thermomagnetic phenomena in layered conductors in the presence of several groups of charge carriers. The thermopower at high external magnetic field is found as a function of the strength and orientation of the field; experimental study of this field dependence permits investigation of the structure of the energy spectrum of the charge carriers.

Giant oscillations of the rate of sound attenuation in layered conductors placed in a magnetic field

The propagation of sound waves in layered conductors with quasi-two-dimensional electron energy spectra is studied theoretically. It is shown that in a magnetic field H the rate of sound attenuation G oscillates with a great amplitude as a function of and of the angle between H and the sound wavevector k, if the charge carriers are capable of drifting along k, and the radius of curvature of their trajectories r is much less than the electron mean free path l but significantly exceeds the wavelength of sound . The diameter of the Fermi surface in the direction orthogonal to the vectors k and H can be determined to a high degree of accuracy from the measured period of the oscillations.

On the propagation of acoustic waves in quasi-two-dimensional conductors in a quantizing magnetic field

The damping of acoustic waves propagating perpendicular to the layers of a quasi-two-dimensional conductor is analyzed for the case of low temperatures, at which the energy quantization of the conduction electrons leads to an oscillatory dependence of the acoustic damping coefficient on the inverse magnetic field. The acoustic damping decrement is found for different orientations of the magnetic field with respect to the layers. It is shown that that a layered conductor is most transparent for an acoustic wave in the case when the magnetic field is perpendicular to the layers.

On the quantum oscillations of the sound attenuation coefficient in layered conductors

The attenuation of a transverse sound wave in a layered conductor with a quasi-two-dimensional dispersion relation of the charge carriers in a quantizing magnetic field is considered. The oscillatory dependence of the sound attenuation coefficient on the inverse magnetic field is analyzed, and the role of Joule losses in the absorption of energy from the sound wave by electrons is ascertained for different orientations of the magnetic field with respect to the plane of the layers.

Thermoelectric Effects in Organic Conductors in a Strong Magnetic Field

The linear response of the electron system of a layered conductor to the temperature gradient in this system in a strong magnetic field is investigated theoretically. Thermoelectric emf is studied as a function of the magnitude and orientation of a strong external magnetic field; the experimental investigation of this function, combined with the study of the electric and thermal resistance, allows one to completely determine the structure of the energy spectrum of charge carriers.

Diamagnetism of layered organic conductors

The temperature dependence of the magnetic susceptibility of layered organic conductors with an arbitrary dispersion law in high magnetic fields is analyzed. It is shown that the quasi-two-dimensional character of the electron energy spectrum of these conductors results in a strong dependence of the diamagnetic contribution to the magnetization on the direction of the applied magnetic field. Experimental investigation of the anisotropy of the magnetic susceptibility makes it possible to study separately the diamagnetic and paramagnetic contributions to the magnetization of layered conductors.

Giant oscillations of the sound absorption in organic conductors in a strong magnetic field

Propagation of acoustic waves in organic layered conductors with quasi-2D electron energy spectrum in a strong magnetic field H is studied theoretically. The rate of sound attenuation G(H) as a function of the orientation and magnitude of the magnetic field and sound wave vector is analysed.