Weak ferromagnetism in the cuprates

An effective held theory that describes the low-frequency spin dynamics in the low-temperature orthorhombic phase of La2CuO4 is derived. The main feat ures of the inherent covert weak ferromagnetism are thus accounted for in a straightforward manner but some of the finer theoretical predictions would require further experimental investigation. In particular, theory predicts the occurrence of magnetic stripes in undoped La2CuO4 which mediate the ob served weak-ferromagnetic transition. (C) 2001 Elsevier Science B.V. All ri ghts reserved.