ESR measurements of the microwave absorption signal associated with weak ferromagnetism in single crystals of Eu2−xGdxCuO4 are presented for X band (9.5 GHz) and L band (1.2 GHz) as a function of the Gd concentration. The strong absorption observed at low

A. BUTERA, A. FAINSTEIN, M. TOVAR, Z. FISK, AND S. B. OSEROFF

JOURNAL OF APPLIED PHYSICS

AMER INST PHYSICS

Lugar: American Institute of Physics; Año: 1996 vol. 79 p. 6577 - 6579

0021-8979

ESR measurements of the microwave absorption signal associated with weak ferromagnetism in single crystals of Eu2−xGdxCuO4 are presented for X band (9.5 GHz) and L band (1.2 GHz) as a function of the Gd concentration. The strong absorption observed at low magnetic fields was interpreted, for samples with low Gd concentration, as due to a field‐induced spin reorientation transition occurring at a critical field Hc, coincident with the in‐plane magnetic anisotropy effective field Heffy. For larger x the Cu‐Gd magnetic interaction needs to be considered leading to smaller Hc values. Our measurements show that for Gd concentrations in the range 0≤x≤1 the experimental data can be very well fitted with parameters derived from previous measurements. This fact indicates that these compounds have nearly the same in‐plane anisotropy effective field, in spite of the small changes in lattice parameters. For x=2 lattice distortions increase causing an Hc larger than the expected one.