The relaxation processes of dislocation systems were studied using two-dimensional dynamic simulations. In order to capture generic features, three physically different scenarios were studied, and power-law decays were found for various physical quantities. The main finding was that all of these were a consequence of the underlying scaling property of the dislocation velocity distribution. Scaling was found to break down at some cut-off time which increased with system size. The absence of an intrinsic relaxation time indicated that criticality was ubiquitous in all of the states studied. These features were reminiscent of glassy systems and could be attributed to the inherent quenched disorder in the position of the slip planes. This effect could be attributed to the quenched random positions of the slip axes and the complex nature of the interactions. The scaling of the time-dependent velocity distribution went with different exponents; depending upon the physical setup. Scaling was cut off due to the finite size, so the system did not possess any inherent time scale. The dislocation system is, therefore, found to behave like a critical one in all cases considered.

Criticality of Relaxation in Dislocation Systems. P.D.Ispánovity, I.Groma, G.Györgyi, P.Szabó, W.Hoffelner: Physical Review Letters, 2011, 107[8], 085506