Weak ferromagnetism induced by the external ield above TN in GdzCuO4

L.B. STEREN; A. FAINSTEIN; M. TOVAR; A. ROUCO ; F. PEREZ ; X. OBRADORS; J. MIRA ; J. RIVAS; S.B. OSEROFF; Z. FISK

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Año: 1993 vol. 73 p. 5710 - 5712

0021-8979

A detailed study of the temperature and field dependence of the dc magnetization near the antiferromagnetic (AF) transition in Gd2CuO4 shows the presence of field‐induced weak ferromagnetism (WF) well above the Néel temperature TN. ac susceptibility measurements indicate TN=266(3) and 282(3) K, for single crystals and ceramic samples, respectively. The shift of the electron‐spin‐resonance line of the Gd3+ ions as a function of temperature T, δHr(T), is compared with the static internal field Hi(T), which describes the coupling between the paramagnetic Gd lattice and the WF component of the Cu moments. Both δHr(T) and Hi(T) show that the WF persists up to ≊50 K above TN. The initial susceptibility (for H≤100 G) presents a contribution in excess of the paramagnetism of Gd ions. For T≥TN, it decays as K(T−TN)−1, with K=0.20(3) emu K mol. The relationship between this result and the strong two‐dimensional AF correlations in these cuprates is discussed.