Magnetic Phase Transitions in Inverse Trirutile-Type Compounds

Magnetic phase transitions in Cr 2 WO 6 , Cr 2 TeO 6 and Fe 2 TeO 6 were investigated from the measurements of magnetic susceptibility and specific heat. The magnetic susceptibility exhibited only broad maxima as a function of temperature around 80 K, 105 K and 240 K for Cr 2 WO 6 , Cr 2 TeO 6 and Fe 2 TeO 6 , respectively, whereas the specific heat showed sharp peaks implying 3-dimensional long-range order at 45 K, 93 K and 206.5 K for the above compounds, respectively. The confusing aspect of these magnetic phase transitions is, however, reconciled with Fisher's notion by means of the temperature derivative of the susceptibility for simple antiferromagnets. Such results give evidence for important short-range low-dimensional magnetic correlations above the 3-dimensional ordering in these materials.