Electric, magnetic, and thermal properties of Ce₂NiGe₃: A kondo lattice compound showing spin glass behavior

The magnetism of Ce₂NiGe₃ was investigated by measuring magnetic susceptibility X, electrical resistivity p, thermoelectric power S, and specific heat C. dc susceptibility shows irreversible behavior at low temperatures. In a low external magnetic field, the field-cooled susceptibility increases monotonically with decreasing temperature. On the other hand, the zero- field-cooled susceptibility shows a peak at 3.5 K, which was estimated as the freezing temperature T_f. The magnitude of the peak decreases with increasing field. No anomalies were found in resistivity and in specific heat at T_f. Instead, a broad peak of the specific heat was observed at a higher temperature 1.3T_f. The magnetic contribution to the specific heat C_m shows a Schottky peak around 60 K, giving the scheme of crystal field splitting: Δ₁ = 135 K and Δ2=498 K. The specific heat coefficient γ was estimated to be 25 mJ/K² mol Ce from the data below 1 K. Magnetic resistivity shows a - 1n T dependence from room temperature to 50 K. The thermoelectric power shows a broad positive peak around 80 K and a negative peak at 20 K. Ce₂NiGe₃ was found to be a new Kondo lattice compound showing spin-glass behavior. Frustration and disorder play a crucial role in the formation of the spin-glass state.