Symmetry Properties of the Transport Coefficients of Magnetic Crystals

A discussion of the symmetry properties of tensors describing the transport properties of magnetic crystals, or of nonmagnetic crystals in applied magnetic fields, is given both from the macroscopic and microscopic points of view. A prescription for the simplification of the form of such a tensor is derived (prescription C) which is based on the use of Onsager's theorem and of Neumann's principle both for the unitary symmetry operations and also, in a modified form, for the antiunitary symmetry operations. This is different from the methods used previously by Birss (prescription A) and by Kleiner (prescription B). While prescription A ignores the antiunitary symmetry operations, the use of these operations is included in both prescriptions B and C. However, prescriptions B and C often lead to different results and it is suggested that experiments based on the Hall effect could be used to determine which of these two prescriptions is correct.