Neutron-scattering study of the transition from antiferromagnetic to weak ferromagnetic order inLa2CuO4

Abstract
Neutron-scattering studies provide direct evidence for a field-driven magnetic transition which originates from the canting of spins out of the CuO2 planes: At the transition between antiferroand ferromagnetic ordering of the canted component of the spins in the layers, the (100) Bragg peak vanishes while the (201) peak appears. Detailed measurements and analysis suggest that the phase transition can be described by the mean-field theory of Thio et al. only close to the Néel temperature.