Field-induced magnetic properties in RCrO4 (R = Pr, Gd, Tb, Tm, and Yb)

RCrO4 oxides (R=Pr, Gd, Tb, Tm, and Yb) have been synthesized at 773K using the corresponding nitrates as precursors. X-ray diffraction data reveal that these samples are single phases and crystallize with the zircon-type structure, showing tetragonal symmetry, space group I4(1)/amd. All the compounds are antiferromagnetic and the Neel temperature, which depends on the R3+ ion, takes values lower than 30 K. The presence of a canting appears to be responsible for the negative values of the magnetic susceptibility found below the compensation temperature. This uncommon phenomenon is, named reversal of magnetization. It is field-dependent, being suppressed at 500 Oe for the TmCrO4 compound. The highest value of the compensation temperature (24K) corresponds to the YbCrO4 oxide. A metamagnetic transition has been observed in all cases at critical fields ranging from 225 Oe (GdCrO4) to 1600 Oe (YbCrO4). (C) 2002 Elsevier Science (USA).