Cluster-glass behavior correlated with spin reorientation in Yb1-x Pr x FeO3

The magnetic properties of polycrystalline Yb1-x Pr (x) FeO3 (0a parts per thousand currency signxa parts per thousand currency sign0.9) are systematically investigated. A cusp in the zero-field-cooled dc magnetization and a frequency-dependent peak in the ac susceptibility reveal the glassy behaviors in this system. Interestingly, for YbFeO3, the freezing temperature T (f) is just in the narrow spin-reorientation region of single-crystal YbFeO3 reported previously. The frequency-dependent peak in the real part of the ac susceptibility can be described by critical slowing down of spin dynamics. The fit to this critical slowing down law yields the values tau (0)=2.79x10(-7) s and zv=2.61. The value of tau (0) is in good agreement with values found in cluster-glass systems. Anomalous thermal hysteresis in the field-cooled magnetization is found in all samples, with a crossover point between the field-cooled cooling and field-cooled warming curves. These anomalous thermal hysteresis behaviors are explained by the competing interaction between the iron-ion subsystem and rare-earth-ion subsystem.