Anomalous low-temperature behavior of PrT2B2C and Pr1-xDyxT2B2C (T = Ni, Co)

We investigated the magnetic, thermal and resistive properties of PrT2B2C (T = Co, Ni) and their solid solutions Pr1-xDyxT2B2C. These compounds behave as normal metallic paramagnets at higher temperatures. At lower temperatures, the parent and the low Dy-substitutions show anomalous features; as an example, their TN are unexpectedly high and, furthermore, the magnetic phase diagram (TN versus x) of Pr1-xDyxT2B2C manifests a strong and non-monotonic dependence on x. At and below liquid helium temperatures and for pressures up to 13 kbar, the parent Pr-based compounds manifest a seemingly quadratic-in-temperature resistive contribution which is attributed to a magnon-electron scattering process. We observed that all isobar resistivity curves can be collapsed onto a single curve when plotted against T/To where To (13-15 K) is a scaling factor. The combined influence of strong crystalline electric field effects and a weak exchange enhancement on the observed properties of these compounds will be discussed. In particular, the manifestation of a weak exchange enhancement in these compounds and in the isomorph nonmagnetic YCo2B2C will be evaluated.