We present magnetic susceptibility, optical, and heat capacitance measurements of
perovskite TiF 3. We find that the optical response favors an insulating state with a local
moment magnetic response consistent with an S= 1/2 local moment per Ti+ 3 ion. Analysis
of the magnetism gives an antiferromagnetic exchange coupling with a net Weiss
temperature of order 25 K. However, the system shows no susceptibility peak at this
temperature scale and appears free of long-range antiferromagnetic order down to 3 K, thus …