The oxyborates show a variety of interesting physical behavior associated with the existence of low dimensional units in their crystalline structure. In this paper we present transport, x-ray, magnetic, and Mössbauer spectroscopy measurements in homometallic ludwigites. These results give evidence of charge localization and reveal an unusual magnetic behavior. We observe the existence of a reentrant weak ferromagnetism as well as the coexistence of paramagnetic and antiferromagnetic spins in ${\mathrm{Fe}}_3{\mathrm{O}}_2{\mathrm{BO}}_3.$

• Received 23 March 1999

DOI:https://doi.org/10.1103/PhysRevB.60.6617