Dislocation model for the TO-period anomaly

Abstract

The dislocation-vibration model can explain both the anomaly in the period of torsional-oscillator (TO) containing solid 4He, i.e. the so-called nonclassical rotational inertia (NCRI), and the anomaly in the shear modulus of solid 4He on the same basis. This dislocation model is extended to understand the amplitude dependence and hysteresis of the TO period by introducing an exponential distribution function for the network pinning lengths of dislocation segments. Pinning and unpinning of dislocations by 3He impurity atoms depending on the history of temperature and stress play an important role. An actual distribution of the network pinning lengths is determined from the experimental data.