Structural characterisation and spin glass behaviour of the new oxide Ba2ScCoO5

Abstract

The new oxide Ba ₂ ScCoO ₅ has been synthesised by solid state reaction and characterised by using both X-ray and electron diffraction techniques. It crystallises in a perovskite-type structure, showing cubic symmetry, space group Pmm [a=4.1400(9) Å]. χ _dc and χ _ac magnetic susceptibility have been measured down to 1.6 K and analysed, indicating the existence of a freezing phenomenon corresponding to a spin glass state. In the high temperature range, χ _dc shows a Curie-Weiss like behaviour, with magnetic correlations starting around T _C =50 K. Below this temperature, a strong irreversibility in χ vs. T curves obtained by zero field cooled and field cooled processes (ZFC/FC) has been detected. A second magnetic transition to a spin-glass phase is observed at T _F =35 K in the ZFC curve. χ _ac measurements performed at different frequencies and magnetic fields also show all the common features characteristic of re-entrant spin-glasses. A possible origin of this magnetic behaviour is proposed and discussed.