Magnetic Susceptibility of Vanadium Difluoride

Measurements have been made of the magnetic susceptibility of VF2 at temperatures between 1° and 300°K. This compound was previously found [J. Appl. Phys. 37, 966 (1966)] to have the rutile structure and to have a gradual maximum in magnetic heat capacity at 27°K and a sharp heat-capacity peak at 7.0°K associated with the development of long-range order. The data were interpreted as indicating that the major exchange interactions between vanadium ions couple together one-dimensional chains of atoms parallel to the c axis. We have measured the magnetic susceptibility of powdered samples and of an oriented crystal sample made by stacking together small needle-like single crystals. The high-temperature susceptibility data show that the net exchange interactions are antiferromagnetic. There is a gradual maximum in magnetic susceptibility near 40°K, consistent with the development of a large amount of one-dimensional short-range order. At 77°K and lower temperature the susceptibility parallel to the c axis is greater than that perpendicular to this direction.