Effects of uniaxial stress on antiferromagnetic moment in the heavy electron compound URu2Si2

Abstract

We have performed the elastic neutron scattering experiments under uniaxial stress ω along the tetragonal [100], [110] and [001] directions for URu2Si2. For ω| [100] and [110], the antifer- romagnetic moment μo is strongly enhanced from 0.02 /μb/U (ω = 0) to 0.22 /μb/U (ω = 0.25 GPa) at 1.5 K. The rate of increase ∂μo/∂ω is roughly estimated to be ∼ 1.0 /μB/GPa, which is much larger than that for the hydrostatic pressure (∼ 0.25 μB/GPa). Above 0.25 GPa, μ0 shows a tendency to saturate similar to the behavior in the hydrostatic pressure. For ω || [001], on the other hand, μo shows only a slight increase to 0.028 μb/U (ω=0.46 GPa) with a rate of ∼ 0.02 /μB/GPa. The observed anisotropy suggests that the competition between the hidden order and the antiferromagnetic state in URu2Si2 is strongly coupled with the tetragonal four-fold symmetry and the c/a ratio, or both. © 2002 The Physical Society of Japan.