The Role of Shear Waves in Electron–Phonon Drag in Potassium Crystals at Low Temperatures

The effect of anisotropy of elastic energy on the electron–phonon drag and thermoelectric phenomena in potassium crystals at low temperatures is investigated in this work. The standard theory of deformation potential is used for longitudinal components of elastic modes. The effect of shear waves on the drag thermoelectric power is taken into account. By comparing the results of calculating the thermoelectric power and lattice thermal conductivity with experimental data, the electron–phonon interaction constant for the shear components of vibrational modes is determined. It is an order of magnitude smaller than for the longitudinal components. It is shown that shear waves make a significant contribution to both the electron–phonon relaxation and the drag thermoelectric power. This contribution is from 28 to 40% of the total drag thermoelectric power for various samples and is four to six times higher than the contribution from longitudinal phonons.