Calorimetric measurements have been made on orthorhombic Er3Ge4 having two crystallographically distinct Er sites. The temperature dependence of specific heat shows a peak near 7 K, confirming the antiferromagnetic ordering of both Er sublattices as suggested by neutron diffraction. A spin reorientation in one of the Er sublattices of the highly canted magnetic structure prevails as a second peak in specific heat around 3.5 K. Both magnetic transitions exhibit no thermal hysteresis. By further taking into account the relatively small contributions from lattice and crystal-field effect, as well as 3R ln 2 for the ordering of all Er3+ with a ground-state doublet, entropy analysis results in a 30 J/mol energy associated with the spin reorientation process.
Physical Review B (Condensed Matter and Materials Physics) 61(1), pp.58-59