Multifractal structure of attractors at the quasiperiodic transition to chaos for electron-hole plasma instability in Ge

The scaling structure of attractors at the transition from quasiperiodicity to chaos is studied for an electron-hole plasma instability in a Ge crystal. The scaling function f({α}) spectrum calculated from the time series of the plasma current oscillation at the onset of chaos is in good agreement with that of a circle-map model. The experimental power spectrum also confirms that the transition to chaos is well described by the circle map. The extrinsic noise effect on the f({α}) spectrum is discussed by using the circle map.