Ground-state symmetry can be broken by an external field. The threshold value of the symmetry-breaking field may be roughly estimated by comparing experimentally the behavior of two identical physical quantities, as functions of the field, for the set of field directions equivalent, with respect to the action, to a group generator. The kinetic coefficients as the functions of magnetic induction B are used as an illustration.

• Received 19 August 1993

DOI:https://doi.org/10.1103/PhysRevB.49.8