Specific heat and magnetization studies of Fe2OBO3, Mn2OBO3, and MgScOBO3 -: art. no. 014406

In this paper we report magnetic and specific heat results for the oxyborates Fe2OBO3 and Mn2OBO3. The former presents L-type ferrimagnetism while the latter presents weak ferromagnetism in distinct ranges of temperature. The Curie constant for Mn2OBO3 is normal while that for Fe2OBO3 is unusually high, as a consequence of short-range ferromagnetic order. The specific heat of both systems at low temperatures is dominated by the magnetic excitations of the ordered magnetic phases. In order to subtract the lattice contribution to the specific heat in these systems, we measured the specific heat of the nearly isostructural, nonmagnetic compound MgScOBO3. The remaining specific heat contains a magnetic part and an additional component associated with charge delocalization.