NONMETALLIC SPIN-GLASS BEHAVIOR BY SPIN FRUSTRATION AT LOW-TEMPERATURE IN NONSTOICHIOMETRIC BASN1-XFEXO3-Y SYSTEM

The solid solutions of BaSn1-xFexO3-y (x=0.00-1.00) have been synthesi zed and investigated as materials being expected to show the spin glas s behavior by spin frustration at low temperature. The Fe ions substit uted in place of Sn ions could have the mixed valence states of Fe3+ a nd Fe4+ ions. The formation of Fe4+ ion began at x=0.50, which has bee n identified by the potentiometric titration and the Mossbauer resonan ce spectra. Magnetic susceptibilities after the zero held cooling (ZFC ) and field cooling (FC) processes have shown the irreversibility at t he compositions of x=0.50, 0.75 and 1.00. This result has indicated th e spin frustration between Fe3+-O-Fe4+, ferromagnetic coupling and Fe3 +-O-Fe3+ or Fe4+-O-Fe4+ antiferromagnetic coupling on the magnetic dom ain boundaries. The field dependence of magnetization at 5 K has shown that there is no net magnetization at zero field in the ZFC process; on the other hand, the remnant magnetization exists in the FC process. In the ZFC process, the magnetization can be relaxed to an equilibriu m resulting in the zero magnetization. In the FC process, however, the ferromagnetic couplings incompatible with antiferromagnetic couplings are frozen on the boundaries and kept on, which shows the spin glass behavior. Copyright (C) 1996 Published by Elsevier Science Ltd.