Variable rate spin freezing and long range antiferromagnetic order in Bi2FeRhO6

A magnetic susceptibility and Mossbauer spectroscopy study of the perovskite Bi2FeRhO6 was undertaken. A freezing start temperature around 270 K was evidenced by both methods. Unlike homogeneous magnetic systems the freezing occurs by involving continuously more and more Fe spins with decreasing temperature over the whole interval down to 4.2 K. At low temperature some evidence for long range antiferromagnetic interactions was found. The Mossbauer data allowed a satisfactory description of the peculiar temperature dependence of the magnetic susceptibility as a superposition of a slain glass antiferromagnetic component and a paramagnetic one. The gradual spin freezing and the absence of percolation derived from the strong influence of the short range interactions, their strengths reflecting the random distribution of the Fe and Rh ions over the B sites of the ABO(3) perovskite. (C) 1997 Elsevier Science S.A.