Low temperature heat capacities of boracites

ABSTRACT

Low temperature specific heat measurements have been performed on Mn₃B₇O₁₃Br and Fe₃B₇O₁₃I boracites. As expected, we observe mag-netic ordering at low temperatures. The Neel temperature of the Fe₃B₇O₁₃I (Fe-I) boracite (31.4 K) differs significantly from the Neel temperature of Fe₃B₇O₁₃Cl (Fe-Cl) boracite (11.8 K, Schnelle et al., 1999). The same is true for the Mn₃B₇O₁₃Br (Mn-Br) boracite, where we observe a transition at 25.9 K, while Schnelle et al. (1999) observed the transition in Mn₃B₇O₁₃Cl (Mn-Cl) boracite at 11 K.

KEYWORDS:

• Ferroelectricity
• ferroic domains
• boracites
• polarizing microscopy
• electron microscopy

Funding

We wish to thank the University of Guadalajara for financial support. One of the authors (AGCG) would like to acknowledge the ICTP Trieste-Italy for financial support of Latin-American Network of Ferrolectric Materials (NET-43).