Orbital ordering against magnetic frustration in ZnV{sub 2}O{sub 4}.

Abstract

Using inelastic neutron scattering we show that upon cooling, ZnV{sub 2}O{sub 4}, a geometrically frustrated cubic antiferromagnet, undergoes a phase transition from a three-dimensional (3D) spin liquid to a one-dimensional (1D) spin chain system. This is evidenced by the change observed at 50 K in the Q-lineshape of the inelastic powder neutron scattering intensity from symmetric to asymmetric that .ts well to the powder-averaged structure factor of 1D spin chains. The transition is due to antiferro-orbital ordering of t{sub 2g} orbitals of the V{sup 3+} (3d{sup 2}) ions to form orbital stripes, that involves the tilting around the c-axis of oxygen tetrahedra residing inside vanadium tetrahedra.