MAGNETIC-PROPERTIES OF NDNI1-XCOXO3 SAMPLES - EVIDENCE OF SPIN-GLASS BEHAVIOR

NdNi1-xCoxO3 perovskites with 0.3≤x≤0.8 show a peak anomaly at low temperatures (28 K) in their χac(T) curve. The frequency dependence of the peak anomaly and magnetization experiments after different thermal cycles, i.e., cooling the samples in the presence of a magnetic field or zero-field cooling, shows that the anomaly is associated with magnetic relaxation processes indicating a new spin-glass transition. X-ray diffraction, transmission electron microscopy, and analysis of the magnetic data agree with the absence of small magnetic impurities which could give smaller relaxation phenomena. A discussion of the microscopic origin of such behavior has also been given. © 1995 The American Physical Society.