SPIN-GLASS TRANSITION IN BACO6TI6O19

Thermomagnetic ac and dc measurements were carried out on polycrystalline BaCo6Ti6O19. The system shows all the characteristic signatures of the spin glass syndrome. dc magnetic susceptibility displays a sharp peak at T(f) = 13.6 K and below this temperature a clear onset of irreversibility between the zero field cooled and field cooled (ZFC-FC) processes is observed. The real part of the ac susceptibility shows also a sharp peak at T(f) which strongly depends on the frequency of the ac magnetic field. The dynamic critical behavior of the system is studied by analyzing the imaginary part of the ac susceptibility in the scope of two models: the activated dynamic scaling and the equilibrium phase transition scaling. The best data collapsing is obtained assuming that a true phase transition occurs at the freezing temperature.