The magnetic hyperfine interaction in superconducting YBa₂(Cu_0.90Fe_0.10)₃O_{7- delta}

Abstract

The temperature dependences of the magnetic hyperfine interactions of three iron species occurring in YBai(C~.uFeo.,)O,.n have been studied by nFe Messbauer rpectroscopy. The analysis was performed using the eigenvalues and eigenvectors of the Hamiltonian of the combined electric quadrupole inleraciions and the magnetic hyperfine interactions for determination of the line positions and intensities. This allows one to derive the electric field gradients wilh their signs and their directions versus the magnetic hyperfine fields. Eridence is given that the magnetic hyperfine splitlings are not due to slow paramagnetic relaxation but are caused by magnetic order probably of a highly anisotropic antiferromagnetic type

Cluster Phase Transition in Spin Glass Systems and Mechanism of High-Tc Superconductivity

“…As discussed in an earlier section, the picture (Fig. 5) [34,35] implying a cluster diameter of %50 # e for a spherical cluster or a frustrated area diameter of %100 # e in Cu±O plane and chain if one assumes the frustration to be confined within the unit cell along the c-axis.…”