Excitation of transverse and longitudinal thermomagnetic waves in anisotropic conducting media in the presence of a temperature gradient T   without an external magnetic fieldH

Abstract

In anisotropic conducting media, the excited thermomagnetic waves at different orientations of the magnetic field and temperature gradient significantly depend on the direction of the anisotropic medium. Theoretical calculations of the electrical conductivity tensor ik  depending on the frequency of the thermomagnetic wave are of scientific interest. In this theoretical work, the frequencies of the thermomagnetic wave at k T   || and at k T ⊥   were found, and it was proven that at longitudinal (k T   || ) and at transverse (k T ⊥   ) the direction of the frequency and growth rate of these waves depends differently on the external magnetic field. The work theoretically studies the conditions for the excitation of thermomagnetic waves. It is indicated that the directions of external fields play a significant role in the appearance of growing waves in the sample. It is shown that, depending on the value of the electrical conductivity tensor ik  , thermomagnetic waves are excited in the longitudinal (i.e. k T   || ) and transverse (i.e.k T ⊥   ) directions. The frequencies of these thermomagnetic waves in both the longitudinal and transverse directions have been calculated. The growth rates of these waves are determined by the values of the inverse electrical conductivity tensor ik  . It has been proven that the excited wave is mainly of a thermomagnetic nature. In theory, the dispersion equation obtained is of algebraically high powers relative to the oscillation frequency. The dispersion equation in both cases (longitudinalk T   || and transverse k T ⊥   ) contains terms in which there are thermomagnetic frequencies in a low degree of frequency. It has been proven that if the value of the electrical conductivity tensor ik  is the same, then the propagation frequencies of thermomagnetic waves are different. The theory is constructed without an external magnetic field 0 0 =Н . In the presence of an external magnetic field, the conditions for the excitation of thermomagnetic waves, and of course the conditions for their growth, will change significantly.