Metamagnetism in the Cr2V4-xMoxO13+0.5x solid solutions.

Abstract

Magnetic investigations were carried out in the temperature range 4.2--300 K, in stationary magnetic fields up to 14 T and in the pulsed magnetic fields up to 38 T on polycrystalline solid solutions of ${\mathrm{Cr}}_{2}$${\mathrm{V}}_{4\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mo}}_{\mathit{x}}$${\mathrm{O}}_{13+0.5\mathit{x}}$ with x=0.0, 0.22, 0.29, 0.35, 0.42, and 0.5. Antiferromagnetic ordering with a N\'eel temperature ${\mathit{T}}_{\mathit{N}}$\ensuremath{\approxeq}13 K and the paramagnetic Curie-Weiss temperature ${\mathit{FTHETA}}_{\mathrm{CW}}$\ensuremath{\approxeq}-22 K was established for all samples. Additionally two metamagnetic thresholds were observed for samples with x=0.0, 0.29, and 0.5 in stationary magnetic fields up to 14 T. All samples have low effective magnetic moments which are far from the saturation expected for the spin-only ${2\mathrm{C}\mathrm{r}}^{3+}$ moment of 6${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$. The metamagnetic state is explained in terms of a large anisotropy, an asymmetric cation-anion-cation superexchange interaction, and an additional superexchange interaction involving the nonmagnetic tetrahedral vanadate and molybdate groups.