MAGNETIC-BEHAVIOR OF A MOTT-INSULATOR YVO3

As one of the members of the ABO3-type pseudoperovskite oxide family, Y1-xCaxVO3 exhibits an insulator-metal transition upon a change in the dopant calcium ion concentration x. We have reinvestigated the magnetic structure of the parent compound YVO3 with use of the neutron scattering technique. YVO3 orders at T(N1)=118 K with the so-called C-type antiferromagnetic structure, but changes to the G-type antiferromagnetic structure at T(N2) approximately 77 K through a first order transition with lattice distortion. These spin structures differ from those of an early study by Zubkov et al. (Sov. Phys.-JETP 39 (1974) 896). The static moment which contributes to the magnetic long range order is extrapolated to be less than 1.6 mu(B) at T=0 K. This value of the static moment is more than 20% smaller than 2.0 mu(B) expected for a localized spin system with S=1, indicating the existence of spin fluctuations in a Mott insulator YVO3.