Novel half-magnetization plateau and nematiclike transition in the S=1 skew chain Ni2V2O7

A quantized magnetization plateau is usually not expected when a classic spin-flop transition occurs in a low-dimensional antiferromagnet. Here, we report an experimental observation of a spin-flop transition followed by a wide half-magnetization plateau in the $S=1$ skew-chain system ${\mathrm{Ni}}_{2}{\mathrm{V}}_{2}{\mathrm{O}}_{7}$. This plateau, which is stabilized in fields of 8--30 T, is realized through an exotic nematiclike phase transition for magnetic fields applied along all three crystallographic axes, resulting in rich anisotropic phase diagrams. We discuss a possible mechanism whereby the magnetic frustration and interchain interactions may cause this half-magnetization plateau, which is in agreement with our exact diagonalization result.