Magnetic anomalies in single crystalline ErPd2Si2
Considering certain interesting features in the previously reported 166Er Moessbauer effect and neutron diffraction data on the polycrystalline form of ErPd2Si2 crystallizing in ThCr2Si2-type tetragonal structure, we have carried out magnetic measurements (1.8 to 300 K) on the single crystalline form of this compound. We observe significant anisotropy in the absolute values of magnetization (indicating that the easy axis is c-axis) as well as in the features due to magnetic ordering in the plot of magnetic susceptibility (chi) versus temperature (T) at low temperatures. The chi(T) data reveal that there is a pseudo-low dimensional magnetic order setting in at 4.8 K, with a three-dimensional antiferromagnetic ordering setting in at a lower temperature (3.8 K). A new finding in the chi(T) data is that, for H//<110>, but not for H//<001>, there is a broad shoulder in the range 8-20 K, indicative of the existence of magnetic correlations above 5 K as well, which could be related to the previously reported slow-relaxation-dominated Moessbauer spectra. Interestingly, the temperature coefficient of electrical resistivity is found to be isotropic; no feature due to magnetic ordering could be detected in the electrical resistivity data at low temperatures, which is attributed to magnetic Brillioun-zone boundary gap effects. The results reveal complex nature of the magnetism of this compound.