Magnetic susceptibility and heat capacity measurements of single crystal TbMnO3

Measurements of the magnetic susceptibility. and heat capacity C on single crystals of the multiferroic TbMnO3 are presented. A non-magnetic isostructural compound, LaGaO3, was used to isolate the magnetic component of the heat capacity. An anisotropic magnetic susceptibility, deviations from Curie-Weiss behaviour and a significant magnetic entropy above the antiferromagnetic ordering temperature T-N1 = 41 K are attributed to a combination of crystal-field effects and short- range order between the Mn moments. Heat capacity in a magnetic field applied along the a axis confirms the saturation of Tb3+ moments in 90 kOe. A hyperfine contribution from the Tb and Mn nuclear moments that may be convolved with a contribution from low- lying Tb crystal- field levels leads to a low- temperature rise in C(T)/T.