High Phonon Frequency Approximation in the Calculation of Phonon Drag Magnetothermopower11The project supported in part by National Natural Science Foundation of China

Abstract

At high magnetic fields and low temperatures the phonon drag magnetothermopower is dominated by phonons with energies much greater than . This fact is used to develop an approximate formula which can be evaluated in a few percent of the time required by the rigorous result. We show that the predominant contribution to the magnetothermopower comes from the transition process in which both the initial Landau level and the final Landau level have the same quantum number where distinguishes the level nearest to the Fermi energy. A double summation over and can therefore be neglected. In the temperature range of to , all the HPFA results agree with the experimental data and the rigorous theoretical results qualitatively. At and , the HPFA results are in fair quantitative accordance with the experimental data and the rigorous theoretical results.