VARIABLE-RATE SPIN FREEZING AND LONG-RANGE ANTIFERROMAGNETIC ORDER INBI2FERHO6

A magnetic susceptibility and Mossbauer spectroscopy study of the pero vskite Bi2FeRhO6 was undertaken. A freezing start temperature around 2 70 K was evidenced by both methods. Unlike homogeneous magnetic system s 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 intera ctions was found. The Mossbauer data allowed a satisfactory descriptio n of the peculiar temperature dependence of the magnetic susceptibilit y as a superposition of a slain glass antiferromagnetic component and a paramagnetic one. The gradual spin freezing and the absence of perco lation derived from the strong influence of the short range interactio ns, their strengths reflecting the random distribution of the Fe and R h ions over the B sites of the ABO(3) perovskite. (C) 1997 Elsevier Sc ience S.A.