Equilibrium magnetization in heavy-ion-irradiated probed by torque and SQUID magnetometry

Measurements of the magnetization and torque on heavy-ion-irradiated (Formula presented) single crystals show that the equilibrium distribution of pancake vortices only depends on the applied field component parallel to the (Formula presented) axis, for fields both above and below the dose equivalent field and also for various irradiation angles with respect to the (Formula presented) axis. This observation is in clear contrast with the irreversible magnetization, which shows a large anisotropy with respect to the field alignment with the columnar defects.