Exponential equilibration by slow cooling in the planar random-anisotropy magnet: experiments and simulations

Neutron measurements of the equilibration of the staggered magnetization in DyAs(0.35)V(0.65)O4 are compared with Monte Carlo simulations of spin dynamics in a planar random-anisotropy magnet. The simulation results are in agreement with striking observed relaxation phenomena: when cooled rapidly to a low temperature no magnetic ordering is observed, but when cooled in small steps an ordered magnetic moment appears which is found to equilibrate exponentially with time at temperatures through and below the transition temperature. In contrast to the freezing of spins in other random systems, the time scale of the relaxation in this system does not increase significantly even at the lowest temperatures.