Abstract
Measurements of magnetization, susceptibility, thermal expansion and electrical resistivity have been carried out on the RMn2 compounds with R=Gd, Tb, Dy, Ho and Er. Magnetization measurements were made on the single crystals for all the compounds. A simple ferrimagnetic structure is observed at 4.2 K for GdMn2, HoMn2 and ErMn2, and an antiferromagnetic one in TbMn2. While, a canted ferrimagnetic structure appears at 4.2 K in DyMn2. The Mn moment deduced from saturation magnetization decreases rapidly from 1.6 μB for GdMn2 to 0.2 μB for HoMn2 with increasing the atomic number of rare earth in the C15 compounds. While, the Mn moment is almost zero in ErMn2 with the C14 structure. Anomalous discontinuities in the thermal expansion and resistivity for GdMn2 and TbMn2 are observed at the magnetic transition temperature where Mn moments lose a long range ordering. It seems likely that the discontinuity is associated with the onset of the Mn moment.
