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

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

PHYSICAL REVIEW B - SOLID STATE

American Physical Society

Año: 1988 vol. 38 p. 257 - 261

0556-2805

We report here experimental data on the crystal-field interaction of gadolinium ions with their environment in GdxEu1-xBa2Cu3O7-δ. 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 8S7/2 ground state of Gd3+ 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-δ (TN≅2.24 K), we analyze the effects of the crystal-field interaction on the magnetic transition.