Space-time symmetry restrictions on the form of transport tensors. II. Thermomagnetic effects

Abstract

For pt.I see abstr. A50562 of 1975. The forms of the magnetothermoelectric power tensor alpha ij(B) for each of the 32 point groups have been obtained by use of the transformation law for field-dependent tensors in conjunction with Neumann's principle. These forms provide a fundamental base for studies of the thermomagnetic effects; the even and odd terms of alpha ij(B) in magnetic induction B are defined as the magneto-Seebeck and Nernst effects respectively. The symmetry restrictions imposed in current expressions for the phonon-drag and diffusion thermopowers are shown to produce different forms for alpha ij(B); these two contributions to the magnetothermoelectric power can be separated by a detailed study of certain components of alpha ij(B). An an example, the form taken by alpha ij(B) for bismuth is discussed. It is shown from both phenomenological and band-structure considerations that the appearance of the Umkehr effect in alpha ij(B) is not anomalous but is a direct result of crystal anisotropy.