Magnetic properties ofDyMn2Ge2from Mössbauer and neutron-diffraction studies

Abstract
Neutron-diffraction and Dy161 Mössbauer measurements on DyMn2 Ge2 are reported. Below 34 K, DyMn2 Ge2 presents a ferrimagnetic structure, while above 40 K an antiferromagnetic order of the Mn moments is inferred. Between 34 and 40 K, these two magnetic phases coexist with an intermediate magnetic phase, the ordered Mn and Dy moments being aligned along the c axis. The saturation hyperfine parameters reveal a fairly pure ‖15/2〉 ground state, i.e., a Dy moment of 10μB. The experimental data explained in the framework of exchange and crystal-field Hamiltonians allowed us to determine the second-(B20) and fourth-order (B40 and ‖B44‖) crystal-field parameters as well as the Dy-Dy, Dy-Mn, and Mn-Mn exchange integrals.