"Magnetic dimensionality of Y2-xDyxBaCuO5"

L. A. BAUM; A. E. GOETA; ROBERTO CARLOS MERCADER; A. L. THOMPSON

Solid State Communications

Año: 2004 vol. 130 p. 387 - 390

0038-1098

In this communication, we report the effect that doping Y2BaCuO5 with Dy has on its two dimensional (2D) magnetic structure.  Pure samples at both ends of the series, as well as samples doped with 1%, 5%, 10% and 25% dysprosium, have been characterised using X-ray diffraction, and AC susceptibility together with neutron diffraction studies on the 1% and 5% samples, which were used to measure the magnetic ordering at low temperatures.  The results show that 1% Dy is enough to disrupt the 2D magnetic ordering turning it into a 3D array.  The low dysprosium concentration indicates that the 3D ordering is achieved without the existence of a rare earth magnetic sublattice.  The change in the ordering temperature from 27 K for the pure Y2BaCuO5 to 16 K for the 1% and 5% Dy compounds, together with the parameters from the AC susceptibility fittings, reveal that the effect of the Dy doping affects the electronic structure of the Cu ions that become involved in the superexchange pathways.  The discrepancy between the parameters obtained by the Curie-Weiss fittings of the real part of the AC susceptibility and the neutron diffraction results, shows that the exchange mechanism deviates from the mean field model for all dysprosium concentrations.