Magnetobreakdown oscillations of Nernst-Ettingshausen field in layered conductors

In the presented report, the Nernst-Ettingshausen effect in layered conductors is investigated. Considering a Fermi surface (FS) consisting of a slightly corrugated cylinder and two corrugated planes distributed periodically in the momentum space, the thermoelectric effects are considered under general assumptions for the value of a magnetic breakdown probability. As a result of an external generalized force, the FS sheets in layered conductors with a multisheet FS appear to be so close that the charge carriers (as a result of magnetic breakdown) can move from one FS sheet to another. In addition, the distribution functions of the charge carriers and the magnetic breakdown oscillations of thermoelectrical field along the normal to the layer, under different values and orientations of the magnetic field, $B$, are calculated. It is shown that if the magnetic field is deflected from the $xz$-plane at an angle $\varphi$, the oscillation part of a thermoelectrical field along the normal to the layer under condition $\sin\varphi\tan\vartheta \gg 1$ is mainly determined with the Nernst-Ettingshausen effect.Comment: 7 pages, 1 figur

Angular dependent magnetothermopower of alpha-(ET)2KHg(SCN)4

The magnetic field and angular dependencies of the thermopower and Nernst effect of the quasi-two-dimensional organic conductor alpha-(ET)2KHg(SCN)4 are experimentally measured at temperatures below (4 K) and above (9 K) the transition temperature to fields of In addition, a theoretical model which involves a magnetic breakdown effect between the q1D and q2D bands is proposed in order to simulate the data. Analysis of the background components of the thermopower and Nernst effect imply that at low temperatures, in the CDW state, the properties of alpha-(ET)2KHg(SCN)4 are determined mostly by the orbits on the new open Fermi sheets. Quantum oscillations observed in the both thermoelectric effects, at fields above 8 T, originate only from the alpha orbit.Comment: 25 pages, 18 figure

Thermoelectric mechanism of electromagnetic-acoustic transformation in organic conductors

The thermoelectric mechanism of electromagnetic-acoustic transformation of the energy in an organic conductor with a quasi–two-dimensional electron energy spectrum (Q2D) placed in an external magnetic field has been considered. The amplitude of the acoustic wave excited by the temperature oscillations in a Q2D organic conductor was calculated for both the isothermal and the adiabatic thermal boundary condition. Angular oscillations of the amplitude resulting from the periodic dependence of the electron velocity on the angle between the normal to the layers and the magnetic field has been observed as expected. A comparison with the inductive mechanism of EMAT is made in order to determine the conditions at which the thermoelectric mechanism is dominant over the inductive one in the presence of a magnetic field. The thermoelectric mechanism of EMAT allows new important information on the electronic structure of the organic layered conductors to be obtained

High frequency properties of a quasi-two-dimensional conductive film

The propagation of a monochromatic longitudinal acoustic wave along the low conductivity axis of a thin quasi-two-dimensional conductive film, in the absence of an external magnetic field, is studied theoretically. It is shown that under certain conditions the formation of both a standing ordinary wave (OAW) and an anomalous acoustic wave (AAW) is possible. The frequency dependence of the amplitudes of both waves is derived. For certain values of the characteristic parameters, the AAW in the film may be dominant. From the resonance conditions for the formation of standing OAW and AAW waves (especially the AAW), it is possible to obtain information about the electronic structure of the quasi-two-dimensional conductors, e.g. the corrugation parameter η or the relaxation properties of the charge carriers. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005