PRESSURE-DEPENDENCE OF THE MAGNETIC ORDER IN RMN(2) (R=RARE EARTH)

Studies of the electrical resistivity were carried out under applied hydrostatic pressure up to 20 kbar and in the temperature range from 1.5 K to room temperature. The heavy RMn2 compounds behave significantly different from those with light rare earths. This is due to the fact that only in the latter case the Mn atoms carry itinerant magnetic moments beyond a critical value of the Mn-Mn distance. Thus in the case of the heavy rare-earth compounds the magnetic order is dominated by the Ruderman-Kittel-Kasuya-Yosida interaction of the rare-earth sublattice, while for the light RMn2 compounds the magnetic properties are mainly determined by the itinerant Mn moments. From the influence of pressure on the temperature-dependent resistivity we deduce a change of the interplay between the different kind of magnetic exchange interactions. As external pressure weakens the itinerant moment a ferromagnetic component is favored within the heavy RMn2 compounds. An extraordinary influence of pressure on spin-fluctuation properties has been observed, yielding ( lnTsf/p=75 Mbar-1) for YMn2. © 1994 The American Physical Society.