Neutron study of magnetic ordering of planar spins in a random anisotropy antiferromagnet: Evidence for quantum tunnelling?

Abstract Large As/V substitutions in DyVO 4 result in planar Dy spins ordering antiferromagnetically in the presence of strong random anisotropy disorder. Neutron measurements on DyAs 0.35 V 0.65 O 4 show the development of sharp but not resolution-limited magnetic diffraction peaks below 1.6 K. Magnetic ordering appears to equilibrate on a time scale of hours as the temperature is reduced in small steps, but, remarkably, the time scale is nearly independent of temperature.