Orbital glass state of the nearly metallic spinel cobalt vanadate

Strain, magnetization, dielectric relaxation, and unpolarized and polarized neutron diffraction measurements were performed to study the magnetic and structural properties of spinel Co1–xV2+xO4. The strain measurement indicates that, upon cooling, ΔL/L in the order of ~10–4 starts increasing below TC, becomes maximum at Tmax, and then decreases and changes its sign at T*. Neutron measurements indicate that a collinear ferrimagnetic order develops below TC and upon further cooling noncollinear ferrimagnetic ordering occurs below Tmax. At low temperatures, the dielectric constant exhibits a frequency dependence, indicating slow dynamics. Lastly, these results indicate the existence of an orbital glassy state at low temperatures in this nearly metallic frustrated magnet.