The magnetic phase diagram of UNi2Si2

Neutron diffraction and magnetization measurements as a function of applied magnetic field are reported for single crystal UNi2Si2. The combined results are used to construct a magnetic phase diagram for applied fields along c. The simple body-centered antiferromagnetic phase, stable in zero field from 55 K to 103 K, is suppressed completely by fields greater than 3.8 T. There is a reentrant triple point at 102.8 K and 2.1 T.