Thermoelectric mechanism of electromagnetic-acoustic transformation in organic conductors

Abstract

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.

Measuring elastic constants using non-contact ultrasonic techniques

“…Recently, non-contact methods of ultrasonic generation and detection have been developed for non-destructive testing (NDT), for example laser ultrasonics and electromagnetic acoustic transducers (EMATs) [10][11][12]. These also have potential for use in materials testing at cryogenic temperatures.…”

Non-contact ultrasonic measurements of the elastic constants of magnetic materials

“…In this case, the magnetic field for these experiments can be used as part of the EMAT in the place of the permanent magnet. EMATs have been used for some recent measurements of single crystals [8,9,11]; however, practically there are still significant issues. EMATs are, by their very nature, sensitive to electrical noise, and their signal to noise ratio when compared with standard techniques can be poor if the environment is electrically noisy.…”