Observation on nonlinear dynamical property of holmium nitrate crystal in low temperature region by measuring time series of ac conductivity

Time series of ac conductivity at 2 kHz along a direction perpendicular to c-axis of holmium nitrate crystal were measured at temperatures T, 12 K T 300 K. Nonperiodic instability (burst) was observed. Temperature variation of the conductivity was found in the region 120 K T 180 K. Power spectral densities derived from the data showed a continuous spectrum proportional to 1/fα with the frequency exponent α≈1. The correlation integrals were derived from the time series data. The temperature variation of the correlation exponent at an embedding dimension was given.