Uniaxial pressure dependence of the antiferromagnetic order in UPt 3

The weak antiferromagnetic order of the heavy-fermion superconductor UPt3 has been investigated by elastic neutron-scattering measurements under applied uniaxial pressure up to 6 kbar along the a and c axes of the hexagonal crystal structure. For p||c the small antiferromagnetically ordered moment of 0.02 μB/U-atom shows a non-linear decrease for increasing pressures and is still not completely suppressed at the maximum applied pressure of 6 kbar. For p||a a significant increase in the magnetic Bragg peak intensity is observed, which suggests an incomplete domain repopulation and confirms the presence of a single-k structure.