Crystal-field interaction in the GdxEu1-xBa2Cu3O7-d superconductors

M.T. CAUSA; C. FAINSTEIN; G. NIEVA; R.D. SÁNCHEZ; L.B. STEREN; M. TOVAR; R. D. ZYSLER; D.C. VIER; S. SCHULTZ; S.B. OSEROFF; Z. FISK; J.L. SMITH

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 1988 vol. 38 p. 257 - 261

1098-0121

We report here experimental data on the crystal-field interaction of gadolinium ions with their environment in GdxEu1-xBa2Cu3O7-d. The ESR spectrum and a Schottky anomaly in the specific heat of dilute samples (x<<1) indicate the existence of a crystal-field splitting of the 8^S_7/2 ground state of     ions of about 1.5 K. We discuss the parametrization of the measured splitting in terms of an effective Hamiltonian, and the microscopic origin of the interaction within the framework of a superposition model. Since the single-ion energies involved are of the same order of magnitude as the energies associated with the magnetic ordering of the Gd3+ moments in GdBa2Cu3O7-d (TN=2.24 K), we analyze the effects of the crystal-field interaction on the magnetic transition.