NONCOLLINEAR MAGNETISM: EFFECTS OF SYMMETRY AND RELATIVITY

Abstract

We give a brief review of the theory of noncollinear order in itinerant electron systems. The theory is an example of the use of the local density-functional approximation for first-principles calculations. We emphasize the role of symmetry arguments since they facilitate the calculations and make the physics of the problem transparent. We choose as examples spiral structures like those found experimentally in fcc Fe, the canted states of U 3 P 4 and weak ferromagnetism in α- Fe 2 O 3 and show that these different phenomena are explained by the theory.