Boundary for weak ferromagnetism in Sm2¡xGdxCuO4 solid solutions.

L.B. STEREN; M. TOVAR; S. OSEROFF

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 1992 vol. 46 p. 2874 - 2878

1098-0121

dc-magnetization and electron-spin-resonance measurements in the solid solutions Sm2-xGdxCuO4 have shown weak ferromagnetism for 1<x≤2. Low-temperature values for the extrapolated spontaneous magnetization associated with a spin canting of the Cu moments, MCu, and the internal magnetic field, HiGd, that polarizes the rare-earth ions have been determined. An exchange coupling constant JGd-Cu=1.0(4) meV has been estimated from the ratio between these two parameters. Hysteresis loops show a small coercive field and differences in the remanent magnetization between field-cooled and zero-field-cooled samples. The possible relation of the boundary for weak ferromagnetism in the series of R2CuO4 cuprates with the existence of local static distortions of the lattice is discussed in terms of Dzyaloshinski-Moriya exchange interactions between the Cu ions.